Processing method, processing apparatus, crystallization method and crystallization apparatus using pulsed laser beam

ABSTRACT

In a laser processing method and a laser processing apparatus which irradiate a processing target body with a laser beam pulse-oscillated from a laser beam source, a processing state is monitored by a photodetector, and the laser beam source is again subjected to oscillation control on the moment when erroneous laser irradiation is detected, thereby performing laser processing. Further, in a laser crystallization method and a laser crystallization apparatus using a pulse-oscillated excimer laser, a homogenizing optical system, an optical element and a half mirror are arranged in an optical path, light from the half mirror is detected by a photodetector, and a light intensity insufficient irradiation position is again irradiated with a laser beam to perform crystallization when the detection value does not fall within a range of a predetermined specified value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromprior Japanese Patent Applications No. 2004-299222, filed Oct. 13, 2004;and No. 2005-275866, filed Sep. 22, 2005, the entire contents of both ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a processing method using a pulsedlaser beam, a processing apparatus using a pulsed laser beam whichcarries out this method, crystallization method using a pulsed laserbeam, a laser crystallization apparatus which carries out this method,and a display device.

2. Description of the Related Art

A machining technology using an excimer laser which is a pulsed laserbeam has been extensively studied and developed for process applicationssuch ablation (evaporation), heating or melting. In recent years, anablation technology has been extensively reviewed with respect to softorganic matters such as plastic, or ceramic, quartz and others which arecalled machining hard materials in particular. Since an excimer laserhas a high photon energy (equal to or above 5 eV) and thereby directlyacts on coupling between molecules, high machining performance isrealized.

The excimer laser processing technology has been extensively used for,e.g., activation using an excimer laser beam intended to activate asemiconductor implanted layer, quartz ablation (evaporation) for forminga fiber grating, machining of a nozzle in an inkjet printer or the like.

In usual laser processing, continuous machining is carried out. Even ifa light intensity of laser irradiation is not normal, machining iscontinued, and a method of again machining (repairing) that part is usedlater. For example, Jpn. Pat. Appln. KOKAI Publication No. 2001-246484discloses a processing method which again performs laser irradiationwith respect to a non-normal machining point if a light intensity oflaser beam irradiation is not normal.

Furthermore, in recent years, an excimer leaser annealing (in this case,laser processing is based on heating) technology which polycrystallizesan amorphous film in particular has been utilized, as a machiningtechnology using a pulsed laser beam, in a technology of realizing highperformance of a thin film transistor which is used in a drive elementsuch as a liquid crystal display.

In order to realize high performance of the thin film transistor, acrystallized silicon thin film having a large grain diameter must beformed. It is known that, when a thin film transistor is formed in acrystal grain, a mobility of the transistor is improved ten times ormore.

As a method of forming a crystal grain having a large grain diameter inan amorphous semiconductor thin film, there is a method described in“Journal of The Surface Science Society of Japan, Masakiyo Matsumura,Vol. 21, No. 5, pp. 278-287, 2000”.

In any application, microfabrication of micron order is required. Ifthere is a failure of laser oscillation in one execution of laserirradiation due to any factor, there occurs a problem of a machiningdefect if nothing is fed back to a laser device. Specifically, whenlaser irradiation is not carried out or a light intensity of laserirradiation is lower than a set value, a region which is not machinedwell is generated, resulting in a reduction in a fair quality ratio (ayield ratio) of a final product.

Further, in crystallization based on laser annealing for other pulsedlaser processing applications, if there is a part which has not beenirradiated with a laser beam or a part in which an irradiation lightintensity of a laser beam has not been enough, this part is notcrystallized at all, or crystallization or activation becomesinsufficient. Therefore, intended uniformity of characteristics orelectrical characteristics cannot be obtained, which is a seriousproblem.

Furthermore, in a case where a laser processing method is used in afield using a laser processing method except the semiconductor field,e.g., machining of an ink discharge hole part of an inkjet head in aninkjet printer, if a laser beam is not applied to a given part or anirradiation light intensity of a laser beam is insufficient, a hole isnot opened or hole machining becomes insufficient, and a yield ratio islikewise reduced in this field, resulting in a serious problem.

Usually, in the excimer laser, ultraviolet radiation has high machiningproperties and ultraviolet radiation demonstrates excellent absorptioncharacteristics with respect to an amorphous semiconductor film incrystallization, and hence the excimer laser is suitable forcrystallization. However, the excimer laser has instability inoscillation characteristics. As a result of actually executing acrystallization process by continuously and extensively applying apulsed laser beam, the excimer laser device has the following drawbacks.Specifically, even though a trigger signal is externally input, nooscillation occurs, or a light intensity is extremely weak (e.g., notgreater than ½ of a set value). In crystallization, even though atrigger signal for light emission control is input to the excimer laserdevice from the outside, a case of no oscillation is generated every1000 pulses and the like. Alternatively, even though the same triggersignal is supplied, a light intensity is extremely weak, and it is notgreater than a set value in some cases. That is because the excimerlaser performs pulsed oscillation by a system based on high-voltagedischarge in a gas. This is characteristics of a current element called“thyratron” used in the excimer laser, which is unavoidable at thepresent day. Although an excimer laser which does not use thyratron hasbeen developed, a large load is imposed on a power supply circuit,thereby reducing reliability or increasing a cost.

This problem is realized as great irregularities of a machiningconformation in a machining process, which is interference of massproduction.

A “light-unemitting shot” described herein means a shot by whichmachining becomes incomplete, and includes both a “case where laserlight is not generated at all” and a “case where a light intensity islow or a light emission time is short”.

As a method of judging whether a shot of a leaser beam is alight-unemitting shot, it is general to adopt a method which places anoptical component which partially divaricates light for laser beamintensity monitoring between a laser beam source and a processing targetmaterial in order to monitor divergent light such as described in PatentReference 1. If it is determined that an intensity of the monitoreddivergent light is not normal, processing which returns to a non-normalprocessing point and again applies a laser beam can be considered. Inthe processing method in the above-described reference, however, thereare the following two problems. That is, firstly, since a position atwhich a laser beam intensity is monitored is not a processing targetmaterial surface, there is a problem that an accurate laser beamintensity on the processing target material surface cannot be grasped.Secondly, moving an X-Y stage to return to an abnormal processing pointand again applying a laser beam has no problem in case of roughprocessing of several-ten μm, but there is a limit in a mechanicalaccuracy in microfabrication which requires a positional accuracy of aprocessing point which is approximately 0.1 to 1.0 μm, and hence thereis a problem that uniform processing is impossible (this problem can besolved by improving the mechanical accuracy).

In view of the above-described problems, it is an object of the presentinvention to provide a laser processing method using a pulsed laser beamwhich again allows a light emitting operation on the scene even if alight-unemitting shot occurs in application of a pulsed laser beam by alaser beam source so that accurate machining is possible without adefect, and a laser processing apparatus using a pulsed laser beam.

Next, in case of forming a liquid crystal drive circuit which forms alarge display screen of a liquid crystal display device in acrystallized region, there are the following problems. In a process ofsequentially moving a pulsed laser beam to a predetermined irradiationposition in a large display screen to thereafter apply the pulsed laserbeam, when any problem exists in laser irradiation of one given shot (anabnormal shot), a serious problem occurs in crystallization of theirradiation position. For example, when laser irradiation is notperformed or when a light intensity of laser irradiation is low,crystallization does not occur, or crystallization becomes insufficient.Therefore, when a transistor is formed in this region, transistorcharacteristics are considerably deteriorated, and a fair quality ratio(a yield ratio) of a final product is thereby lowered.

Further, besides the laser crystallization process, in activation of asemiconductor implanted layer based on laser annealing, when a laserbeam is not applied or when an irradiation light intensity of a laserbeam is low, this part is not activated at all, or activation becomesinsufficient. Therefore, intended electrical characteristics cannot beobtained, which is a serious problem in quality management.

In view of the above-described problems, it is an object of the presentinvention to provide a crystallization method which detects an abnormalshot and again performs shooting to thereby improve a reduction in ayield ratio of crystallization even if the abnormal shot occurs inirradiation of a laser beam for crystallization, a laser crystallizationapparatus and a display device.

BRIEF SUMMARY OF THE INVENTION

In view of the above-described problems, it is an object of the presentinvention to provide a phase shifter capable of homogenizing acrystallization size in an irradiation region, a manufacturing method ofthe phase shifter, and a laser annealing apparatus.

Thus, a processing method according to one aspect of the presentinvention which relatively moves an irradiation position obtained by apulsed laser beam emitted from a laser beam source and a processingtarget body and sequentially irradiating a predetermined position of theprocessing target body with the pulsed laser beam to perform machiningcomprises: a step of monitoring a light intensity of light reflected bythe processing target body in accordance with the pulsed laser beamemitted from the laser beam source; a step of irradiating the nextirradiation position of the processing target body with the pulsed laserbeam when the monitored light intensity is normal; a step of againirradiating a light intensity insufficient position of the processingtarget body when it is determined that the light intensity isinsufficient as a result of the monitoring; and a step of storing theirradiation position based on the pulsed laser light as light intensityinsufficient irradiation position information when the light intensityis insufficient.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a processing target bodyhaving, e.g., an excellent yield ratio.

The step of monitoring the light intensity in accordance with the pulsedlaser beam preferably determines that the light intensity isinsufficient when the light intensity to be monitored is not greaterthan a preset light intensity.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a processing target bodyhaving, e.g., an excellent yield ratio.

Light reflected by the processing target body is preferably the pulsedlaser beam reflected by the processing target body or light obtained byreflecting light emitted from a probe light source different from thelaser beam source by the processing target body.

The pulsed laser beam applied to the processing target body preferablyhas an intensity of the pulsed laser beam on a two-dimensional planehomogenized by a homogenizing optical system.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a processing target bodyhaving, e.g., an excellent yield ratio.

The result of the monitoring is preferably displayed, recorded in astorage medium and/or output to a printer during processing.

According to the above-described method, the conventional drawbacks areeliminated, and a processing history is displayed in the apparatus, orremains in a laser processing apparatus, a storage medium and/or aprinter output during processing, and hence analysis of a defect or ayield ratio can be facilitated, thereby providing an excellentprocessing target body.

A processing method according to another aspect of the present inventionwhich relatively moves an irradiation position obtained by a pulsedlaser beam emitted from a laser beam source and a processing target bodyand sequentially irradiates a predetermined position of the processingtarget body with the pulsed laser beam to thereby perform processingcomprises: a step of optically monitoring a processing state of theirradiation position in accordance with the pulsed laser beam emittedfrom the laser beam source; a step of irradiating the next irradiationposition of the processing target body with the pulsed laser beam whenit is determined that processing is normal as a result of themonitoring; a step of again irradiating a non-normal processing positionof the processing target body when it is determined that processing isnot normal as a result of the monitoring; and a step of storing theirradiation position obtained by the pulsed laser beam in case of theabnormal processing as non-normal processing irradiation positioninformation.

According to the above-described method, the conventional problems areeliminated, and it is possible to provide a processing target bodyhaving, e.g., an excellent yield ratio.

A processing apparatus using a pulsed laser beam according to stillanother aspect of the present invention comprises: a laser beam sourcewhich emits a pulsed laser beam; a homogenizer optical system whichhomogenizes an intensity of a laser beam oscillated by this laser beamsource in a two-dimensional plane; monitoring means for monitoring anintensity of light reflected by the processing target body; means forirradiating the next irradiation position of the processing target bodywith the pulsed laser beam when it is determined that the lightintensity is normal as a result of monitoring by the monitoring means;and means for again irradiating a light intensity insufficient positionof the processing target body when it is determined that the lightintensity is insufficient as a result of the monitoring.

A processing apparatus using a pulsed laser beam according to yetanother aspect of the present invention comprises: a laser beam sourcewhich emits a pulsed laser beam; a homogenizer optical system whichhomogenizes an intensity of the laser beam emitted from this laser beamsource in a two-dimensional plane; processing means for irradiating aprocessing target body with the homogenized laser beam to perform laserprocessing with respect to this processing target body; an opticalmonitoring portion which optically monitors a processing state of anirradiation position in accordance with the pulsed laser beam emittedfrom the laser beam source; first irradiating means for irradiating thenext irradiation position of the processing target body with the pulsedlaser beam when it is determined that processing is normal as a resultof the monitoring; and second irradiating means for again irradiating anon-normal processing position of the processing target body when it isdetermined that processing is not normal as a result of the monitoring.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a processing target bodyhaving, e.g., an excellent yield ratio.

A crystallization method according to one aspect of the presentinvention which irradiates a non-single-crystal semiconductor film witha laser beam emitted from a laser beam source which performs pulsedoscillation to thereby carry out crystallization has: a homogenizationprocessing step of homogenizing an intensity of the laser beam in atwo-dimensional space; a step of forming a light intensity gradient inan intensity distribution of the laser beam subjected to thehomogenization processing; a laser beam irradiation step of irradiatingthe non-single-crystal semiconductor film with the laser beam having thelight intensity gradient formed therein; a laser beam detection step ofdetecting whether the laser beam is a laser beam having a predeterminedspecified value; an abnormal shot position information storage step ofstoring an irradiation position of the non-single-crystal semiconductorfilm as abnormal shot position information when the detected value doesnot fall within a range of the specified value; and a laser beamre-irradiation step of reading the stored abnormal shot positioninformation and irradiating a position corresponding to the readabnormal shot position information with the laser beam.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a non-single-crystalsemiconductor film having, e.g., an excellent yield ratio.

The laser beam detection step preferably comprises: a step of dividingthe laser beam into a crystallization laser beam and an abnormal shotdetection laser beam by an optical component provided between the laserbeam source and the non-single-crystal semiconductor film; and a step ofdetecting the abnormal shot laser beam, comparing the detected laserbeam with a predetermined specified value, and outputting the abnormalshot laser beam as an abnormal shot when the abnormal shot laser beamwhich is not greater than this specified value is detected.

The laser beam detection step is preferably a step of detecting a changein the non-single-crystal semiconductor film by reflected light inassociation with an irradiation timing of the laser beam.

The specifies value is preferably a laser intensity of an energyquantity with which the non-single-crystal semiconductor film is melted.

The laser beam detection step is preferably a step of using aninstrument to measure an irradiation part of the non-single-crystalsemiconductor film irradiated with the laser beam.

The specified value is preferably equal to a specified value used incrystallization by previous irradiation.

The laser beam re-irradiation step is preferably a step of readingabnormal shot position information by the laser beam irradiation stepwhen, the laser beam irradiation step with respect to all predeterminedirradiation positions of the non-single-crystal semiconductor film iscompleted, and again applying the laser beam.

At least one of the irradiation position information and the abnormalshot position information obtained by the laser beam irradiation step ispreferably displayed in a display device.

A laser crystallization apparatus which irradiates a non-single-crystalsemiconductor film with a laser beam emitted from a laser which performspulsed oscillation to thereby carry out crystallization has: laser beamdetecting means for detecting whether the laser beam is a laser beamhaving a predetermined specified value; and a computer which compares adetected value detected by this laser beam detecting means with apreviously stored specified value, stores irradiation positioninformation of the non-single-crystal semiconductor film as abnormalshot position information when the detected value does not fall within arange of the specified value, and reads the abnormal shot positioninformation to again issue a laser beam irradiation command afteranother light receiving region is irradiated with the laser beam andlaser beam irradiation of the non-single-crystal semiconductor film isterminated.

A laser crystallization apparatus which irradiates a non-single-crystalsemiconductor film with a laser beam emitted from a laser which performspulsed oscillation to carry out crystallization has: a laser beam sourcewhich performs pulsed oscillation with respect to a laser beam; ahomogenizer optical system which is provided in a laser optical pathfrom this laser beam source and performs homogenization processing withrespect to an intensity of this laser beam in a two-dimensional space;an optical element which is provided in a laser optical path from thishomogenizer optical system and forms a light intensity gradient in thehomogenized laser beam; a sample stage which is provided in a laseroptical path from this optical element, on which a non-single-crystalsemiconductor film whose light receiving region is at least partiallymelted when the laser beam is received is mounted, and which can move toanother predetermined light receiving region; laser beam detecting meansfor detecting whether the laser beam is a laser beam having apredetermined specified value; and a computer which compares a detectionvalue detected by this laser beam detecting means with a previouslystored specified value, stores irradiation position information of thenon-single-crystal semiconductor film as abnormal shot positioninformation when the detected value does not fall within a range of thespecified value, and reads the abnormal shot position information toagain issue a laser beam irradiation command after another lightreceiving region is irradiated with the laser beam and laser beamirradiation of the non-single-crystal semiconductor film is terminated.

A region corresponding to each predetermined pixel of anon-single-crystal semiconductor film provided on a substrate isirradiated with a crystallization laser beam by the lasercrystallization method mentioned above to form a crystallized region,and a transistor is formed in this crystallized region.

According to the above-described method, the conventional drawbacks areeliminated, and it is possible to provide a non-single-crystalsemiconductor film having, e.g., a yield ratio.

According to the present invention, it is possible to obtain a laserprocessing method using a pulsed laser beam and a laser processingapparatus using a pulsed laser beam, which again allow a light emittingoperation on the moment even if a light-unemitting shot occurs inapplication of the pulsed laser beam by a laser beam source, therebyeffecting accurate processing without a defect.

Furthermore, according to the present invention, it is possible toexcellently perform laser crystallization without lowering a yield ratiosince an abnormal shot is detected to thereafter perform repairing evenif the abnormal shot occurs in application of a laser beam forcrystallization.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and obtained by means ofthe instrumentalities and combinations particularly pointed outhereinafter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention, andtogether with the general description given above and the detaileddescription of the embodiments given below, serve to explain theprinciples of the invention.

FIGS. 1A to 1D are views each showing a laser intensity distribution forexplaining an embodiment of the present invention, and FIG. 1D is a viewshowing a processing state of a processing target body;

FIG. 2 is a system block diagram illustrating a laser processingapparatus according to a first embodiment of the present invention;

FIG. 3 is a flowchart illustrating a method according to the embodimentin a process order;

FIG. 4 is a system block diagram illustrating a configuration of acomputer depicted in FIG. 2;

FIG. 5 is a flowchart illustrating a method of determining a specifiedvalue of the embodiment in a process order;

FIG. 6 is a plan view showing a processing state of a processing targetbody for explaining a process of determining a specified value of by thelaser processing apparatus depicted in FIG. 2;

FIG. 7 is a characteristic view showing a relationship of a processingdegree with a step shape of ablation processing being standardized withrespect to a detection value of a photodetector by the laser processingapparatus depicted in FIG. 2;

FIG. 8 is a photodetector output waveform chart when a laser beam isapplied, which illustrates a process of determining the specified valueof the laser processing apparatus depicted in FIG. 2;

FIG. 9 is a system block diagram illustrating a laser processingapparatus according to a second embodiment of the present invention;

FIG. 10 is a system block diagram illustrating a laser processingapparatus according to a third embodiment of the present invention;

FIGS. 11A to 11C are cross-sectional views illustrating a fourthembodiment of the present invention;

FIG. 12 is a plan view illustrating a crystallized processing targetbody according to a sixth embodiment of the present invention;

FIGS. 13A to 13F are system block diagrams illustrating embodiments of alaser crystallization apparatus according to the present invention;

FIG. 14 is a flowchart illustrating the crystallization method depictedin FIG. 13A;

FIG. 15 is a system block diagram illustrating a configuration of acontrol system depicted in FIG. 13A;

FIG. 16 is a view illustrating a process of determining a specifiedvalue depicted in FIG. 13A;

FIG. 17 is a view illustrating experimental data when determining aspecified value of the crystallization apparatus and the crystallizationmethod depicted in FIG. 16;

FIG. 18 is a view illustrating a process of determining a specifiedvalue according to the fourth embodiment of the present invention;

FIG. 19 is a view of experimental data when determining an irradiatedpart measurement value in the crystallization apparatus and thecrystallization method according to the embodiment of the presentinvention;

FIG. 20 is a view showing experimental data when determining a specifiedvalue in a laser processing apparatus and a laser processing methodaccording to the embodiment depicted in FIG. 13A;

FIG. 21 is a view illustrating a relationship between the FIG. 13Aoptical system and a crystallization target substrate;

FIG. 22 is a view illustrating an optical configuration of anillumination optical system depicted in FIG. 21;

FIG. 23 is a perspective view illustrating a configuration of TFT formedon substrate to be processed depicted in FIG. 21;

FIG. 24 is a perspective view illustrating a configuration of a displaydevice in which TFTs depicted in FIG. 23 are formed;

FIG. 25 is a partially cutaway plan view of a display panel illustratinganother embodiment of FIG. 1D; and

FIG. 26 is a partially cutaway plan view of a display panel illustratinganother embodiment of FIG. 1D.

DETAILED DESCRIPTION OF THE INVENTION

An object of an embodiment according to the present invention will nowbe described with reference to FIG. 1A to 1D. First, a description willbe given on a judging experiment which is a criterion of judging whethera state in this excimer laser processing apparatus is good or bad, i.e.,whether an irradiation light intensity of a laser beam is normal orabnormal. A laser beam from a beam source was homogenized by ahomogenizer or the like, and it was shaped into a beam 31 which isrectangular in a two-dimensional plane shown in FIG. 1A and has ahomogeneous laser light intensity. At this time, FIG. 1B shows aone-dimensional light intensity distribution in a direction indicated bya line 32, and FIG. 1C shows a one-dimensional light intensitydistribution in a direction indicated by a line 33. A processing targetbody 47, e.g., a resin substrate (a polyimide substrate in this case)such as a plastic substrate or a polyimide substrate was irradiated withsuch a beam 31 with a fixed laser beam intensity, e.g., a laser beamintensity of 700 mJ/cm² to perform ablation processing.

On the processing target body 47, as shown in FIG. 1D, irradiation ofone shot was carried out from an upper left position with the substrateand the beam 31 being relatively moved in a row direction. Upontermination of one-shot irradiation in one row, an irradiation spot wasmoved in a column direction to a position which is not superimposed onthe already irradiated region and then moved toward the next row so thatan irradiation position can be sequentially shifted to “1”, “2”, . . .in the row direction in accordance with each shot, and irradiation wascarried out at fixed intervals. Further, when the irradiation positionreached a right end in the second row, it was moved to a left end in thenext third row below the second row, and irradiation was again likewiseperformed to the right end. In this manner, irradiation was carried outwith the same intensity at fixed intervals while being associated with astage X, Y. FIG. 1D shows this state. With this irradiation, a lightintensity of each pulsed oscillation output from the laser apparatus wasrecorded as a processing history in a memory in association with anirradiation position of the laser shot.

Here, examining the processing target body 47 irradiated in theabove-described process, it was revealed that there exists a shot bywhich ablation does not occur at all at each irradiation positionindicated by 34 in FIG. 1D. Checking a record of an oscillationintensity of the laser apparatus at such a shot position, it wasunderstood that the oscillation intensity of the excimer laser isextremely small. As a result of the extensive examination, it wasrevealed that no occurrence of ablation at each irradiation positiondenoted by 34 was caused by a light-unemitting shot.

The present inventors discovered that such a light-unemitting shot isresults in insufficiency of a light intensity for processing so thatprocessing based on ablation processing cannot be performed ornon-normal processing such as occurrence of a part where an ablationarea is small or ablation is insufficient is generated in some cases.

In order to avoid such non-normal processing, the following processingapparatus using a pulsed laser or a processing method using a pulsedlaser can obtain a laser processing target surface which can beaccurately processed without a defect allover. Further, a processingtarget body having an excellent yield ratio can be obtained and,specifically, using such an apparatus or method in an ablationprocessing step can reduce or eliminate a part which is not ablated or apart where ablation is insufficient, thereby improving a yield ratio.

First Embodiment

A laser processing apparatus using a pulsed laser beam and a laserprocessing method using a pulsed laser beam will now be described withreference to FIG. 2. FIG. 2 is a system block diagram showing a laserprocessing apparatus using a pulsed laser beam. In these examples, anexcimer laser beam source 41 (e.g., XeCl, KrF, ArF or the like) having alarge output is used as a pulsed laser beam source, but the presentinvention is not restricted thereto, and a solid laser such as a thirdharmonic wave or fourth harmonic wave of Q switched YAG laser may beused.

As shown in FIG. 2, an attenuator 42 which controls a light intensity ofa pulsed laser beam 40 and a homogenizing optical system 43 whichhomogenizes an intensity of a laser beam on a two-dimensional plane aresequentially arranged in an exit optical path of the excimer laser beamsource 41 which emits the pulsed laser beam 40.

It is to be noted that a position denoted by reference numeral 55corresponds to a primary image forming plane (a focal plane) of thehomogenizing optical system 43, and an optical element 44 which shapesan intensity distribution of a laser beam homogenized by thehomogenizing optical system is arranged at this position. The opticalelement 44 is an optical component having a function of shaping a lightintensity distribution, and it is possible to use a metal mask having arectangular opening portion or an optical mask using as a base materialquartz or the like obtained by depositing a non-translucent material ona translucent optical component of quartz or the like and removing thenon-translucent material in a rectangular shape by etching. Moreover, itis also possible to use a phase modulation element or an opticaldiffraction element having an irregular shape obtained by performingetching or film deposition on a surface of a base material such asquartz.

A mirror 45 which reflects the pulsed laser beam 40 90 degrees isprovided in the exit side optical path of the homogenizing opticalsystem 43. The pulsed laser beam 40 reflected by this mirror 45 istransmitted through a projection lens 46, and again image-formed on asurface of a substrate which is a processing target body 47 provided ata focal position of this projection lens 46 (a secondary image formingplane 56). As a result, the processing target body 47 mounted on an X-Ystage 48 is processed.

On the other hand, a part 40A of the pulsed laser beam 40 reflected bythe processing target body 47 is condensed by a lens 40B, and receivedby a photodetector 49 which detects a light intensity. Here, in regardto reflection, reflected light which is reflected 180 degrees has thehighest intensity, but the pulsed laser beam to be applied has a highintensity, and reflected light is also generated at any other angledepending on a surface state or a structure of the processing targetbody 47. Therefore, this reflected light includes information of aprocessing state of the processing target body 47.

A received light signal intensity is input to a computer 51 through asignal line 50, the computer performing analysis of a light intensitydetection signal and control for allowing a crystallization apparatus toautomatically execute a process.

The computer 51 judges an analysis result of the light intensitydetection signal, and the computer 51 transmits a movement signal to adrive mechanism DM through a signal line 53 in order to control thestage 48 to move, or transmits an oscillation control signal to thelaser beam source 41 through a signal line 52 depending on a result ofthis judgment. If the computer 51 determines that the light intensity isa normal intensity which is not smaller than a specified value as aresult of the judgment, the laser beam 40 and the processing target body47 are relatively moved to the next irradiation position by movementcontrol.

When the laser beam irradiation position is set to the next processingtarget position, the computer 51 performs oscillation control withrespect to the laser beam source 41. On the other hand, if the computer51 determines that the light intensity is insufficient as a result ofthe judgment, the computer 51 again performs oscillation control withrespect to the laser beam source 41 with a relative position of thelaser beam 40 and the processing target body 47 being set in a suspendedstate.

The photodetector 49 which is characteristic of the apparatus accordingto this embodiment will now be described in detail. Here, the lens 40Bwhich condenses the reflected light 40A on the photodetector 49 is oneof methods which lead light to the photodetector 49, and it may be aconvex lens or a cylindrical lens. Further, a light reducer may beinserted or a wavelength filter may be inserted between the processingtarget body 47 and the photodetector 49 in order to control a detectionsensitivity.

As the photodetector, a power meter which is manufactured by OPHIR Ltd.,and has a model number PE50BB is used. However, the photodetector 49 isnot restricted to this model, and any photodetector having a sufficientoptical sensitivity and a dynamic range can suffice. Furthermore, it ispossible to use a photodetector which does not have an opticalsensitivity with respect to an excimer laser beam but has a detectionsensitivity in a regular visible light region, and can detect an excimerlaser beam as visible light by using on a front surface of thephotodetector 49 a filter which converts an ultraviolet ray into visiblelight or a wavelength conversion plate on which a fluorescent materialis applied, the fluorescent material producing fluorescent in a visiblelight region on a wavelength side longer than an excimer laserwavelength by ultraviolet irradiation.

A light intensity value detected by the photodetector 49 is input to thecomputer 51. The computer 51 compares the input value with a specifiedvalue which is a light intensity required to perform ablation withrespect to the predetermined processing target body 47, and controlspredetermined processing depending on the input value which is notsmaller or greater than the specified value. FIG. 3 shows its processflowchart, and a description will now be given with reference to theflowchart of FIG. 3. Like reference numerals denote parts equal to thosein FIGS. 1 and 2, and their tautological explanation will be eliminated.

First, the computer 51 carries out a process 61 (P-61) which calls, ascontrol data for the stage 48, processing information of a substratewhich is the processing target body 47 to be processed, e.g.,irradiation position information like coordinate information of x-y suchas shown in FIG. 1D. Then, it performs a process 62 (P-62) which callsthe specified value which is a predetermined normal irradiation value.Such calling processes are carried out through a sub-routine. Data ofthe specified value is previously stored in a storage device (a storagemedium such as a floppy disk, a silicon memory, a hard disk (HD), amagneto optical disk (MO) a compact disk (CD), a DVD and others)provided in the computer 51. The calling processes read data from thisstorage device.

Then, the computer 51 executes a process 63 (P-63) which moves the stage48 to a coordinate position of X and Y specified by a predeterminedprogram so that the processing target body 47 is set at a position whereit is irradiated with the laser beam.

Subsequently, the computer 51 performs oscillation control over thelaser beam source 41 to effect a first laser irradiation process 64(P-64). At the same time, it executes a process 65 (P-65) which measuresa laser light intensity by using the photodetector 49, and carries out aprocess 66 (P-66) which transmits a detected value (a photodetectionvalue) to the computer 51 through a signal line 50 and then displaysthis value.

Further, a judgment is made upon whether the photodetection valuedetected by the photodetector 49 falls within a range of the specifiedvalue (P-67). In the judgment of a process 67 (P-67), the photodetectionvalue detected by the photodetector 49 is compared with the specifiedvalue, and the computer 51 performs a process 68 (P-68) which judges endof the program (P-68) if the compared photodetection value falls withinthe range of the specified value (normal irradiation). If it isdetermined that the machining process has not been terminated yet as aresult of the judgment based on the process 68 (P-68), a machiningprocess of the next irradiation position is executed. That is, a commandsignal to move the stage 48 is transmitted in order to carry out anirradiation process for the next irradiation position so that theprocessing target body 47 can be set to a position where it should beirradiated with the laser beam, and the drive device DM moves the stage48 in response to this command, thereby continuing the processing.

On the other hand, if the detected photodetection value does not fallwithin the range of the specified value (non-normal irradiation),namely, when laser irradiation is not carried out or when the laserlight intensity is smaller than the specified value, the computer 51again performs the next control over the laser beam source 41 on themoment in order to apply the laser beam. The computer 51 does nottransmit a command signal for moving the stage 48 to the drive deviceDM, but carries out a process 69 (P-69) of alert display by which laserirradiation is again performed, and then again effects the process 64(P-64) of pulsed laser irradiation without moving the processing targetbody 47. At this time, the photodetector 49 likewise detects a lightintensity of a pulsed laser beam, and judges whether irradiation isnormal or non-normal.

The computer 51 compares a detected light intensity value with thespecified value to make a judgment, and transmits a command signal formoving the stage 48 to the drive device DM for the next process if thedetected value falls within the range of the specified value. This drivedevice DM operates the stage 48 in response to this command to move theprocessing target body 47 to the next processing position. Afterconforming movement of the processing target body 47, the computer 51performs oscillation control over the laser beam source 41 to generatethe laser beam 40, thereby continuing the ablation processing.

Here, if light-unemitting shots are continuously generated or the numberof light-unemitting shots is larger than that in regular processing, itcan be considered that any problem exists in laser oscillation, anoptical component and others, and hence the computer 51 may display analert to inform an operator, or a function of transmitting an alertsignal may be provided to the computer 51 managing an apparatusoperating status. As to alert display, a probability that a detectedlight intensity value with respect to the number of times of oscillationcontrol of the laser beam source 41 does not fall within the range ofthe specified value may be calculated, and the calculated probabilitymay be always displayed.

Furthermore, if an irradiation light intensity of the pulsed laser beamdoes not fall within the range of the specified value, the processingposition information is stored in the storage device in the computer 51.Storage of this processing position information is effective whenperforming reconfirmation in an inspection process after the processing.

When machining was carried out with respect to all parts of theprocessing target body 47 which should be processed, an end judgment ismade, and the processing of the substrate which is the processing targetbody 47 is terminated. In this case, in order to preserve a processingstatus and a processing history with respect to the processing targetbody 47, the specified value used when processing the processing targetbody 47 and the photodetection value of the photodetector are saved asdata in the storage device (a storage medium such as a floppy disk, asilicon memory, a hard disk, a magneto optical disk (MO), a compact disk(CD, a DVD and others), the data is output to a printer or the like,then the processing target body 47 is collected, and the next processingtarget body 47 is mounted on the stage 48, thereby continuing the sameprocessing.

Here, the predetermined specified value is a value obtained in advanceby an experiment, a value given by an approximate calculation formulabased on an experimental value, or a previous processing value. Thespecified value is affected by manufacturing conditions (a compositionor the like) of the intended processing target body 47. It can beconsidered that the manufacturing conditions have an influence on thespecified value because a laser ablation phenomenon greatly concerns aphotochemical reaction of the processing target body 47 and its statusis affected by a coupling state of constituent elements.

Moreover, values such as daily environmental variables (a temperature,humidity and others), an individual difference of the excimer laser beamsource 41, a frequency in use, a deterioration status, an individualdifference of a reflection factor (reflective index) or a transmissionfactor of each optical component and others are also reflected in thisspecified value, and a different value is set in accordance with eachprocessing apparatus. Additionally, this specified value changes fromday to day (since environmental variables, a frequency in use, adeterioration status are concerned), and hence a processing status ofthe processing target body 47 which has been already processed is fedback. Actually, a monitoring standard substrate is prepared, an ablationstatus of the processing target body 47 is confirmed by periodicallyperforming a step evaluation (a contact type step instrument, a lasermicroscope, an optical microscope, an interference microscope) and anevaluation experiment of an ablation status (a change in opticalreflectance before and after processing) or the like, and the confirmedstatus is reflected in the specified value.

A control system of the ablation process performed by the FIG. 2computer 51 will now be described with reference to FIG. 4. FIG. 4 is asystem block diagram showing the computer 51. Like reference numeralsdenote parts equal to those in FIG. 2, thereby eliminating theirdetailed explanation.

To a bus line 300 are connected inputting/outputting means 301, acentral processing unit (which will be referred to as a CPU hereinafter)302 which executes a crystallization process based on a previouslystored operation program, a memory 303 which stores a predeterminedoperation program, and a display device 304 which displays input/outputinformation.

Further, to the bus line 300 are also connected a control/analysiscomputing machine (PC) 305 which outputs a controls signal used toperform ablation processing, a stage drive mechanism information storagedevice 306 which stores a program which is used to automatically movethe stage on which a processing target substrate is mounted with apredetermined process, and a laser device control information storagedevice 307 which stores a program for controlling the pulsed laser beamsource 41 which outputs a pulsed laser beam for ablation processing.

Furthermore, to the bus line 300 is connected a measurement/analysisinformation storage device 308 which stores a program which measures alight intensity of each pulsed laser beam emitted from the pulsed laserbeam source 41 and judges whether the pulsed laser beam is applied tothe next irradiation position or the pulsed laser beam is again emittedbased on the measured value. Moreover, a normal laser beam informationstorage device 309 which stores a previously obtained light intensityrequired to perform ablation processing as normal light intensityinformation is connected to the bus line 300.

An embodiment of an ablation processing step will now be described withreference to FIGS. 2 and 4. First, before executing the ablationprocessing step, the CPU 302 reads the program stored in the memory 303to move the processing target body 47 from an optical path of the laserbeam 40 or the stage 48 which supports this processing target body 47 toa predetermined retraction position, and performs positioning of theprocessing target body 47. Then, the CPU 302 reads an ablationprocessing program from the memory 303, and controls emission of thepulsed laser beam set to a light intensity for the ablation processingfrom the laser beam source 41.

The emitted laser beam is applied to the processing target body 47through the optical system, and a part of the laser beam reflected fromthe processing target body 47 is detected by the photodetector 49. TheCPU 302 stores light intensity information detected by thisphotodetector 49 in the memory 303 through the inputting/outputtingmeans 301. The CPU 302 reads normal light intensity informationpreviously obtained for crystallization from the normal laser beaminformation storage device 309 based on a program read from themeasurement/analysis information storage device 308, compares thisinformation with the detected light intensity information, outputsjudgment information indicating whether the light intensity falls withina range of a normal intensity, and stores it in the memory 303 inassociation with irradiation position information.

If it is determined that the light intensity falls within the range ofthe normal intensity, the CPU 302 displays this result in the displaydevice 304, and stores it in the normal laser beam information storagedevice 309. At the same time, the CPU 302 reads a program required tomove the stage 48 from the stage drive mechanism information storagedevice 306, and outputs control information used to move the stage 48 tothe next irradiation position to the drive mechanism DM.

On the other hand, if it is determined that the light intensity does notfall within the range of the normal intensity, the CPU 302 decides thatthis judgment information is indicative of an output defect, displaysthis result in the display device, and stores it in themeasurement/analysis information storage device 308. At the same time,the CPU 302 reads a laser device control program from the laser devicecontrol information storage device 307, and controls the laser beamsource 41 so that emission of the laser beam is again controlled.

At this time, the CPU 302 drives the stage 48 to stop so thatreapplication control is performed, or a reapplication operation can beexecuted in the next laser beam emission period. Such a processing stepis repeated to extensively execute the ablation processing step.

A procedure of determining a specified value in an example of theablation processing will now be described with reference to FIG. 5 as aflowchart. Like reference numerals denote parts equal to those in FIGS.1 to 3. The specified value is determined by irradiating the processingtarget body 47 with the laser beam from the laser beam source 41 whilesequentially increasing a laser beam intensity F (a laser fluence F) andactually measuring a threshold value as the specified value with whichprocessing can be sufficiently performed. In this case, the ablationprocessing is carried out by laser irradiation so that a depressed part(a depth) is formed on the processing target body.

First, the above-described increasing quantity (ΔF) of the laser beamintensity is determined (P-72). It is desired that this value is muchgreater than a scattering value between shots of the laser beam source41. Then, an upper limit value (Fup) of the laser beam intensityrequired for laser processing for machining is determined (P-73). Thisupper limit value of the laser beam intensity is determined whileconsidering an oscillation capability of the laser beam source 41, e.g.,an excimer laser beam source, an appropriate range at the time ofcontinuous processing, a processing margin and others. The processingtarget body 47 is irradiated with a laser beam intensity to which theincreasing quantity AF is sequentially added (P-74, P-75), a lightintensity is measured by the photodetector 49, and an output value isstored (P-76). The stage 48 is sequentially moved (P-77), and machining(processing) is continued. When the laser beam intensity has reached theupper limit value Fup (P-78), machining (processing) is aborted. Theprocessing target body 47 was taken out, and evaluation was carried outin the next step (P-79). This is an off-line evaluation, and a processedstate was evaluated by using a laser microscope this time.

FIG. 6 shows a substrate which is the processed processing target body47. Numeric FIGS. 1, 2, 3, 4 . . . indicate processing orders, and eachrectangle indicates a processed region obtained by one laserirradiation. As the number is increased from 1, the laser beam intensityis increased ΔF to perform processing. No ablation processing wascarried out in regions having the numbers 1 and 2, but a depth of theablation processing is increased as the number grows from 3 to 5, andthe depth became fixed in regions having the number 6 and the subsequentnumbers. Therefore, the laser beam intensity when processing was carriedout at the sixth time is a lower limit value required to performsufficient processing. If the laser beam intensity is smaller than thislower limit value, the processing is insufficient, and hence a value ofthe photodetector 49 with this lower limit value is determined as thespecified value (P-80). In this case, although the depth became fixed inthe sixth and subsequent regions, the fixed depth is not necessaryobtained depending on a processing material. In this case, when a givendepth is reached, it is determined that sufficient processing has beencarried out, and a value of the photodetector 49 with this lower limitvalue can be determined as the specified value.

FIG. 7 shows a concrete experimental result. In FIG. 7, a horizontalaxis shows a value detected by the photodetector 49 in the laserprocessing apparatus used in this experiment. Since a fixed step can beobtained with an optimum value, a vertical axis shows a processingdegree obtained by standardizing a step shape based on the ablationprocessing as a ratio of a processed step with respect to the fixedstep. It was revealed that the processing degree increases in accordancewith a measured value of the photodetector 49.

The processing target body 47 used in evaluation is the three samepolyimide substrates (A, B and C), and the ablation processingexperiment was conducted by using these three substrates. A laserprocessing apparatus which performs machining was used as an evaluationapparatus, and the processing target bodies 47 which are continuouslyprocessed in the same machining day were used to conduct the experimentin order to avoid an influence of environmental variables as much aspossible. As a result, a region having a photodetection value which isnot smaller than 1.9 mW obtained by the photodetector 49 has a valuecorresponding to a laser irradiation quantity required to obtain anexcellent processed shape, and this value was determined as a specifiedvalue.

This experiment evaluates a processing conformation by using the lasermicroscope in order to obtain the specified value in the ablationprocessing and thereby determines the specified value of thephotodetector, but the present invention is not restricted to thismethod, and there is, e.g., a method of evaluating a processed surfaceby using a stylus type step instrument. Moreover, as to determination ofthe specified value, a previous specified value may be stored andadopted as a current specified value.

Additionally, in the above-described evaluation experiment, since theevaluation takes time, it is difficult to immediately perform feedbackin the current processing step.

If many of factors causing light-unemitting shots correspond to a casewhere oscillation of the laser does not occur even if a trigger signalis input, it is good enough to set a specified value to a current valueobtained by a discharge current detection circuit in a power supplycircuit of the laser beam source 41 so that whether the laser beamsource 41 has performed oscillation can be judged, and it is possible todetermine the specified value without necessarily conducting anexperiment which measures the processing conformation. A method ofsetting the specified value in this case will now be described withreference to FIG. 8.

FIG. 8 shows photodetection values of the photodetector 49 before andduring laser irradiation. Here, a signal which fluctuates around 25 (anarbitrary unit: a. u.) is output before laser beam irradiation. This isan output signal due to noise of the photodetector 49, and depends onperformance and an individual difference of the photodetector 49 andenvironments of the photodetector (a temperature, humidity, stray lightand others).

Here, even if laser oscillation is not performed, this noise is called adetection value of the photodetector 49, and an output signal from thephotodetector 49 is called a detection value even though a laser beam isnot actually detected. That is because a signal from the photodetector49 is generically called a detection value of the photodetector 49 sincevarious cases of laser oscillation such as a case where a laser beam isnot applied or a case where weak light is applied can be assumed.

When a laser beam is applied, a detection value of the photodetector 49is increased, and a signal of approximately 65 (a. u.) is output in caseof FIG. 8. This increase in a signal intensity depends on an S/N ratio(a signal-to-noise ratio) of the photodetector 49, a light quantity oflight separated from an optical component and others. In order to judgewhether a laser beam is applied, an accurate judgment can be made as adifference between a detection value before this laser irradiation and adetection value during the laser irradiation is large, but an increasein a signal which is approximately 1.50 times is required at minimum.

Even if a light quantity of a laser beam separated from an opticalelement to enter the photodetector 49 is increased, a detection value isincreased. However, a very strong laser beam enters the photodetector49, sensitivity of the photodetector 49 is deteriorated because anexcimer laser beam has a short wavelength and a high energy. Therefore,it is not preferable for the photodetector 49 to output an extremelyhigh detection value.

As a specified value which is used to judge whether laser irradiationhas been carried out, a normal judgment cannot be made unless a valuecorresponding to a detection value which is at least 1.20 times adetection value before laser irradiation is determined as the specifiedvalue.

In the first embodiment, as shown in FIG. 2, the pulsed laser beam 40Areflected from the processing target body 47 is detected by thephotodetector 49, and a signal indicative of this beam detection valueis transmitted to the computer 51 through the signal line 50.

Second Embodiment

A second embodiment is an example in which a processed state of aprocessing target body 47 is optically observed and a desired processedstate and an unprocessed state are judged. FIG. 9 is a system blockdiagram illustrating an embodiment of an ablation apparatus whichoptically observes and evaluates a processed state (a result) of theprocessing target body 47. Like reference numerals denote parts equal tothose in FIGS. 1 to 8, and their detailed explanation will beeliminated.

As shown in FIG. 9, the second embodiment is an example where a part ofthe processing target body 47 processed by a pulsed laser beam 40 from alaser beam source 41 is illuminated by additionally prepared opticalobserving means so that a processed result is observed. A probe lightsource 54 may be a lamp or a semiconductor laser which performscontinuous oscillation. The processed position is irradiated with alaser beam emitted from this probe light source 54.

A photodetector 49 is arranged at a position where a laser beam of theprobe light source 54 which has been reflected from the processedposition of the processing target body 47 can be received. Thisphotodetector 49 detects evaluation information of a processed state ofthe processed position. The photodetector 49 transmits a detectionsignal indicative of this information to a computer 51 through a signalline 50. An evaluation method according to this embodiment uses thepulsed laser beam 40 and the different probe light source 54, andutilizes a fact that a reflection factor from the processed positionwhen normal processing has been carried out by the laser beam isdifferent from a reflection factor from the processed position whenprocessing has not been normally executed.

Therefore, quality of processing is grasped and determined based onwhether a signal value monitored by the photodetector 49 is a valueobtained when normal processing has been carried out(non-normal/normal).

As described above, according to this embodiment, the photodetector 49can acquire a value in which a processed status of the processing targetbody 47 is sufficiently reflected. Therefore, it is possible to get freeof a trouble (deterioration in an optical component, accidentalattachment of foreign particles and others) between a laser beamintensity monitoring position and the processing target body 47 whichcannot be eliminated by a conventional method which makes a judgmentbased on a partial light intensity in an optical path. As a result, thejudgment, which is stable for a long time, on quality of processing withrespect to a material of the processing target body 47 can be accuratelymade.

Third Embodiment

As shown in FIG. 10, a third embodiment is an example in which a laserbeam source 41 and a second laser beam source 404 are prepared and aprocessed position of a processing target body 47 is illuminated byadditionally prepared optical observing means to observe each processingresult each time. A pulsed laser beam 401 emitted from the laser beamsource 41 is combined with a pulsed laser beam 402 emitted from thelaser beam source 404 by a half mirror 403, and the laser beam emittedfrom each laser beam source becomes a pulsed laser beam 40 aftertransmitted through the half mirror 403. Usually, one of the laser beamsource 41 and the laser beam source 404 is used to perform processing.

A photodetector 49 detects evaluation information of a processed stateof the processed position, and quality of processing is grasped anddetermined based on a fact whether a signal value monitored by thephotodetector 49 is a value obtained when normal processing has beencarried out (normal/non-normal). If a value of the photodetector 49indicates insufficient processing, processing at the same position(retry) is repeatedly carried out. In case of using one laser beamsource only, if the laser beam source has a defect, retry due toinsufficient processing is performed endlessly. Therefore, when apredetermined number of times of retry has been effected, the apparatusmust be stopped. In this embodiment, however, if the predeterminednumber of times of retry has been carried out, it is determined that thelaser beam source has a failure, and processing can be restarted byusing another laser. For example, in a case where retry due toinsufficient processing is frequently performed when using, e.g., thelaser beam source 41, a computer 51 determines to stop the laser beamsource 41 and switches to the second laser beam 404, thereby improvingthroughput.

Although the description has been given as to the ablation processing inthe foregoing embodiments, the present invention can be likewise appliedto a processing method which forms a crystalline semiconductor thin filmfrom a non-single-crystal semiconductor film which is used for a TFT asa semiconductor device. Further, the processing for a semiconductor thinfilm does not have to be restricted to a crystallization method, and itcan be used for, e.g., activation of a semiconductor implanted layerbased on laser annealing as the laser processing method. A descriptionwill now be given as to activation based on laser annealing which isanother application of the laser processing method.

Fourth Embodiment

This embodiment is an example applied to a process of forming a veryshallow pn junction, which is superior to a conventional junction, byusing an excimer laser as means for activating an impurity in order toform a pn junction in a shallow region of a semiconductor thin film.

Referring to FIGS. 11A to 11C, a method of activating an impurity of asemiconductor will be described taking activation of an impurity of an ntype thin film transistor as an example. FIG. 11A is a cross-sectionalstructural view of a thin film transistor before ion implantation. Anunderlying insulating film 180 having a thickness of approximately 1 μmis provided on a substrate, e.g., a glass substrate 179, and apolysilicon film 170 having a film thickness of approximately 50 nm isformed in an island-like shape on this underlying insulating film 180.This polysilicon film can be formed by a method of changing amorphoussilicon into polysilicon by a laser, a method of changing amorphoussilicon into polysilicon by oven annealing, or a method of directlydepositing polysilicon by CVD (chemical vapor deposition). Furthermore,a gate insulating film 192, e.g., SiO2 having a thickness of 100 nm isdeposited on this polysilicon film. A gate electrode 191, e.g., aluminum(a film thickness: 200 nm) is formed on the polysilicon film 170 throughthis gate insulating film 192. Moreover, SiO2 having a film thickness of100 nm is deposited as a passivation film on the gate electrode 191 byCVD.

Then, as shown in FIG. 11B, ion implantation 194 of phosphor as animpurity is carried out. Then, the gate electrode 194 is used as a mask,a channel region 172 directly below the gate electrode 194 remains aspolysilicon, and phosphor is implanted into the polysilicon film 170 sothat an amorphized source region 171 and an amorphized drain region 173are formed. A general method then performs oven annealing and restorescrystallinity of the source region 171 and the drain region 173 toactivate the impurity, but laser activation is processed as follows.

As shown in FIG. 1C, a laser 195 is used to continuously emit laserbeams. Then, the amorphized source region 171 is recrystallized to be aphosphor-doped source region 174, and the amorphized drain region 173 isrecrystallized to be a phosphor-doped drain region 175. That is becausethe source and drain regions are heated by laser irradiation, and hencecrystallinity is restored and phosphor is doped with a highconcentration, thereby effecting activation.

In case of activation based on laser annealing using regular laser beamirradiation (FIG. 11C), a light-unemitting shot is a serious problemleading to a reduction in a yield ratio. A part where a light-unemittingshot has occurred is not activated since it has no light emission or nolight emission intensity required for activation, and an element havingconsiderably deteriorated electrical characteristics is formed.

As a method of solving this problem, performing the laser processingmethod using the laser processing apparatus according to Embodiments 1and 2 can achieve formation of an excellent element having no part whichis not activated, thereby solving the problem. In the laser processingmethod, a specified value for a photodetection value is obtained by anactivation evaluating experiment. In the activation evaluatingexperiment, for example, a processing target body 47 having an impurityimplanted therein is used as an test substrate, and a change in a sheetresistance of an impurity implanted layer is measured by a four-terminalmethod using laser irradiation. If activation is sufficiently achieved,a low resistance value is presented, and a specified value is therebydetermined based on whether this value is a satisfactory value increation of an element. The activation evaluating experiment is notrestricted to this method, and activation can be obtained by any method,e.g., electrical measurement or physical measurement, and determined byusing these methods.

Although the present invention can be used in a liquid crystal displayapparatus as a semiconductor element and a display device using asemiconductor element, it is not restricted thereto, and it can belikewise applied to, e.g., an organic EL display apparatus.

Fifth Embodiment

Although the description has been given as to the laser processingmethod and the laser processing apparatus used in the semiconductorfield in the foregoing embodiments, the problem of a light-unemittingshot is also an important problem in crystallization using an excimerlaser.

The present inventors discovered that the laser processing apparatus andthe laser processing method according to the present invention areeffective in processing based on a laser annealing apparatus which isused as laser processing.

Sixth Embodiment

An excimer laser crystallization apparatus using the present inventionwill now be described. Like reference numerals denote parts equal tothose in FIGS. 1A to 11C, and their detailed explanation will beeliminated. A non-single-crystal semiconductor thin film (an amorphoussilicon thin film in this case) deposited on a processing target body 47was irradiated with a laser beam having a fixed laser beam intensity(350 mJ/cm²), thereby effecting crystallization (polycrystal silicon inthis case). The processing target body 47 is moved in such a manner thata pulsed laser beam is intermittently applied to the processing targetbody in the order of reference numerals 1, 2 and 3 from an upper leftpart, and annealing processing is carried out every shot. In thisprocess, for example, during processing of the parts indicated by thenumbers 3 and 10, when an alert is displayed in the laser displaydevice, the processing target body 47 is not moved, and the second laserbeam shot is applied to the same position. When an oscillation intensityof the excimer laser was compared with a record of an oscillationintensity of the laser beam source 41 at a shot position displayed asthe alert, it was revealed that the oscillation intensity of the excimerlaser is extremely small. Therefore, a non-normal value was detected asdescribed above, a shot denoted by 70 was able to avoid a laserannealing defect, i.e., a laser processing defect based on alight-unemitting shot.

A further object of the embodiment according to the present inventionwill now be described again based on FIG. 1. First, a description willbe given as to a crystallinity evaluating experiment which can be acriterion of judging quality, i.e., an irradiation light intensity of alaser beam is a normal value which satisfies a specified value or anabnormal value which does not satisfy the specified value in the excimerlaser processing method and processing apparatus.

A laser beam emitted from a pulsed oscillation laser beam source as alight source has an intensity in a two-dimensional space homogenized bya homogenizing optical system, e.g., a homogenizer set on an exit side,and this laser beam is shaped into a laser beam 31 which is rectangularin a two-dimensional plane shown in FIG. 1A and has a homogeneous laserbeam intensity. In this laser beam 31, a one-dimensional light intensitydistribution on a central line 32 is homogenized as shown in FIG. 1B,and a one-dimensional light intensity distribution on a central line 33is homogenized as shown in FIG. 1C. Such a laser beam 31 was used tocrystallize an amorphous thin film, e.g., an amorphous silicon thin filmformed on a glass substrate as a non-single-crystal semiconductor filmwith a fixed laser beam intensity of, e.g., 700 mJ/cm².

Although the amorphous silicon thin film was quoted as an amorphous thinfilm herein, a polycrystal thin film having a microcrystal structure maybe included in the amorphous thin film in some cases. The polycrystalthin film described herein means a film having a polycrystal structureaboundingly including microcrystals (not greater than sub-micron) in thefilm and has a fine crystal structure, but crystallization in thepresent invention intends to form a crystal structure including crystalgrains having a size of several microns or several-ten microns. In thatsense, a polycrystal thin film having a microcrystal structure whichdoes not have intended crystal grains is determined as an amorphous thinfilm. An amorphous thin film (an amorphous silicon film in this example)of a crystallization target substrate 47 was irradiated with the laserbeam 31 to fuse an irradiation region, and this region was crystallizedin a temperature reduction process. A stage was moved in directions Xand Y in accordance with each pulse irradiation of the pulsed laserbeam, and the irradiation region was sequentially shifted by moving anirradiation position of one shot in the direction X in the order of “1”,“2”, “3” . . . from an upper left part as shown in FIG. 1D so that thecrystallization target substrate 47 is subjected to a crystallizationprocess (the substrate and the laser beam 31 are relatively moved). Uponcompletion of irradiation of one row in the direction X, the irradiationposition was shifted in a direction of the next row (a direction of −Y),and irradiation was again sequentially carried out at a fixed pitch inaccordance with each shot (FIG. 1D). In FIG. 1D, a laser irradiationregion by one shot is illustrated as a rectangular frame.

In FIG. 1D, an irradiation region denoted by a dotted line isillustrated as a part 34′ where crystallization is not carried out atall. This uncrystallized region is produced due to an abnormal shot ofthe excimer laser beam source 221. This abnormal shot positioninformation is stored. Upon completion of the crystallization processwith respect to one crystallization target substrate 227, the abnormalshot position information is read, and a crystallization laser beam isagain applied to execute the crystallization process. As a result, thecrystallization target substrate 227 can be crystallized without anon-crystallized region due to an abnormal shot, thereby terminating thecrystallization process. As the embodiment shown in FIG. 1D, each laserirradiation region illustrated as the rectangular frame is a regioncorresponding to each pixel of a display device, e.g., a liquid crystaldisplay device. That is, the regions corresponding to respective pixelsall become crystallized regions, thereby obtaining a defect-free displaydevice. In this crystallized region, a pixel switching transistor isformed with a thin film transistor structure.

Using the following laser crystallization apparatus and lasercrystallization method with respect to a part which is not crystallizedor insufficiently crystallized due to such an abnormal shot can achievea manufacturing process having excellent transistor characteristics inall aspects.

Seventh Embodiment

An embodiment of each of a laser crystallization apparatus and a lasercrystallization method will now be described with reference to FIG. 13A.In these examples, an excimer laser beam source 221 (e.g., XeCl, KrF,ArF and others) is used as a light source, but the present invention isnot restricted thereto.

As shown in FIG. 13A, an attenuator 222 which controls energy density ofa laser beam 220 to a predetermined light intensity required forcrystallization and a homogenizing optical system 223 which homogenizesan in-plane light intensity of the laser beam are sequentially arrangedon an exit side of the excimer laser beam source 221 which emits thepulsed laser beam 220.

It is to be noted that a position denoted by reference numeral 235 is aposition which has an image forming relationship with a crystallizationtarget substrate 227 with respect to an image forming optical system226, and an optical element 224 which shapes an intensity distributionof the laser beam 220 homogenized by the homogenizing optical system 223is arranged at this position. The optical element is an opticalcomponent which has a shaping function in order to prevent light frombeing transmitted through a part where a light intensity of peripherallight of the laser beam is attenuated. The optical element 224 is, e.g.,a metal mask having a rectangular opening portion or an optical maskhaving, as a base material, quarts or the like obtained by depositing anon-translucent material on a translucent optical component formed ofquarts or the like and removing the non-translucent material in arectangular shape by etching.

An optical component which separates a crystallization laser beam and adetection laser beam from each other, e.g., a half mirror 225 whichperforms 90-degree reflection and partial transmission is arranged in anexit optical path of the homogenizing optical system 223. The laser beamreflected by the half mirror 225 is applied and image-formed as acrystallization laser beam 220 a on the crystallization target substrate227 mounted on a sample stage (a stage) 228. A light receiving region ofan amorphous silicon film 236 on the crystallization target substrate227 is melted, and crystallized in a temperature reduction process.

Further, on the other hand, a detection laser beam 220 b transmittedthrough the half mirror 225 is received by a photodetector 229, and itsreceived light signal intensity is input to a computer 231 whichperforms light intensity detection and analysis through a signal line230.

The half mirror 225 as an optical component which separates thecrystallization laser beam 220 a and the detection laser beam 220 b fromeach other and the photodetector 229 which are characteristic of thelaser crystallization apparatus will now be described in detail. Thehalf mirror 225 described herein means an optical component whichreflects and transmits therethrough incident light, but does not meanthat its transmission quantity and reflection quantity are equal, and anoptical component with which reflected light and transmitted light exitcan suffice. The half mirror 225 is a mirror but not restricted to atabular mirror only, and it may have a polygonal shape or a prism shape.Furthermore, it does not have to separate two lights by using phenomenaof reflection and transmission, and it is good enough to separate thecrystallization laser beam and the detection laser beam from each otherby an optical component. Moreover, the present invention is notrestricted to the two split lights, and it is good enough to split lightinto a plurality of lights so that one is applied to the crystallizationtarget substrate 227 for crystallization and the other enters thephotodetector 229 for light intensity detection.

As the photodetector, for example, an optical power meter which ismanufactured by Opto Science, Inc and has a model number FL250A-EX isused. However, the photodetector 229 is not restricted to this model,and the photodetector 229 having light sensitivity with respect to theexcimer laser beam 220 b can suffice. Additionally, it is possible touse the photodetector 229 which does not have light sensitivity withrespect to the excimer laser beam 220 b but has detection sensitivitywith respect to a regular visible light region, and detects the excimerlaser beam 220 as visible light by using on a front surface of thephotodetector 229 a filter which converts ultraviolet light into visiblelight or a filter on which a fluorescent material is applied to generatefluorescence in a visible light region on a wavelength side higher thanan excimer laser wavelength by ultraviolet radiation.

A detection value detected by the photodetector 229 is input to thecomputer 231, and compared with a specified value predetermined as acrystallization energy value, and then processed. When a pulsed laserbeam whose value is not greater than the specified value is emitted, thecomputer 231 stores this irradiation position information as abnormalshot position information in a storage device. The crystallizationprocess using the pulsed laser beam is not stopped, and irradiation ofthe next crystallization pulsed laser beam is continued. FIG. 14 shows aflowchart of this crystallization process, and the crystallizationprocess will now be described with reference to FIG. 14. Like referencenumerals denote parts equal to those in FIGS. 1A to 13F, therebyeliminating their tautological explanation.

As the above-described storage device, there is a storage device such asa floppy disk (a registered trademark), a silicon memory, a hard diskdrive (HD), a magneto optical disk (MO), a compact disk (CD), a DVD orthe like. Set values required for crystallization are called from thisstorage device, and initialization is carried out. Here, the necessaryset values are control data for the stage 228, an irradiation positionto be processed, threshold values of an irradiation energy and apredetermined crystallization energy, and others (a step 241). Then, thecomputer 231 moves the stage 228 to a planned irradiation position atwhich the crystallization target substrate 227 should be irradiated witha laser beam (a step 243).

The computer 231 performs oscillation control over the excimer laserbeam source 21 to emit a first laser shot (a step 244). At this time,the photodetector 229 detects a laser beam intensity of a laser beamseparated by the half mirror 225 (a step 245), and transmits thedetected value (a photodetection value) to the computer 231 through asignal line 230.

Then, the computer 231 transmits a command signal to move the stage 228for processing at the next step, and the drive device moves the stage228 in response to this command, thereby continuing the laser beamirradiation processing (steps 243 to 248). When processing has beencarried out with respect to all planned irradiation positions of thecrystallization target substrate 227 to be processed, an end judgment ismade (a step 248). The computer 231 compares a predetermined specifiedvalue with values detected by the photodetector 229, and judges whetherthe detected values fall within a range of the specified value (a step249). If all the detected values fall within the range of the specifiedvalue, it is determined that the processing has been completed, wherebythe processing of the crystallization target substrate 227 isterminated.

On the other hand, if a detected value of even one shot does not fallwithin the range of the specified value, i.e., if there is a shot whichdoes not satisfy the specified value, the computer 231 reads abnormalshot position information, sets a planned irradiation position at whichlaser beam irradiation is performed (a step 250), and transmits acommand signal to move the stage 228 to the irradiation position. Thedrive device moves the stage 228 in response to this command, therebycontinuing the laser beam irradiation processing (steps 243 and 244). Atthis time, the photodetector 229 detects the laser beam 220 b andoutputs a detected result to the computer 231 (a step 245).

In this manner, the computer 231 sequentially reads the abnormal shotposition information, controls the crystallization target substrate 227to be moved to a corresponding position, then performs irradiationcontrol of the pulsed laser beam 220, and executes the crystallizationprocess.

If all the detected values fall within the range of the specified valuein this manner, it is determined that the processing has been completed,whereby the processing of the crystallization target substrate 227 isterminated. Here, abnormal light-emitting shots may be continuouslygenerated, or the number of abnormal light-emitting shots may be largerthan that of regular processing in the same crystallization targetsubstrate in some cases. In such cases, since it can be considered thatlaser oscillation, an optical component or the like has any problem, thecomputer 231 may display an alert in the crystallization apparatus 201to inform an operator, or may have a function of transmitting an alertsignal to the computer managing an apparatus operating status.

In this case, in order to maintain a processing status and a processinghistory of the crystallization target substrate 227, a specified valuewhen processing the crystallization target substrate 227, i.e., aphotodetection value obtained by the photodetector 229 is saved as datain the storage device (a storage device such as a floppy disk (aregistered trademark), a silicon memory, a hard disk, a magneto opticaldisk (MO), a compact disk (CD), a DVD or the like), and a step ofoutputting this data to a printer or the like may be provided.Thereafter, the crystallization target substrate 227 is collected, andthe next crystallization target substrate 227 is carried in and mountedon the stage 228, thereby continuing the same laser beam irradiationprocessing.

Here, the predetermined specified value is a laser energy quantityrequired to fuse an irradiation region of amorphous silicon, and it isobtained by an experiment in advance or given by an approximatecalculation formula based on an experimental value. The specified valueis also affected by a film thickness, a film quality and film formingconditions of an amorphous thin film which is an intendedcrystallization target film of the crystallization target substrate 227as well as a film quality, a film thickness and others of an insulatingfilm around this amorphous thin film. That is because a crystallizationphenomenon caused by laser irradiation greatly concerns a cooling statusof this amorphous thin film, and it can be considered that this coolingstatus is affected by peripheral films.

Furthermore, an individual difference, a frequency in use and adeterioration status of the excimer laser beam source 221, values suchas an individual difference of a reflection factor or a transmissionfactor of each optical component and others are also reflected in thisspecified value, and a different value is set in accordance with eachlaser crystallization apparatus. Moreover, this value varies from day today (since a frequency in use and a deterioration status of the laserare concerned), and hence a processing status of the processedcrystallization target substrate 227 is fed back.

Actually, a crystallization target substrate for monitoring acrystallization status of the crystallization target substrate 27 isused to periodically conduct a crystallinity evaluating experiment of,e.g., a grain diameter of a crystal grain (a scanning electronmicroscope (SEM), a transmission electron microscope (TEM)), measurementof crystallinity (an electron backscattering process (EBSP), an X-raydiffraction method (XRD), a reflection high energy electron diffractionmethod (RHEED)), a crystallization status (a change in a lightreflection factor before and after processing, a change in electricalcharacteristics based on a four-terminal measurement method or the like,a change in an absorption factor in an infrared region using FTIR) andothers, and obtained results are reflected in the specified value.

A control system for the crystallization process using the computer 231depicted in FIG. 13A will now be described with reference to FIG. 15.FIG. 15 is a system block diagram of the computer 231. Like referencenumerals denote parts equal to those in FIG. 13A, thereby eliminatingtheir tautological detailed explanation.

To a bus line 300 are connected inputting/outputting means 301, acentral processing unit (which will be referred to as a CPU hereinafter)302 which executes a crystallization process based on a previouslystored operation program, a memory 303 which stores a predeterminedoperation program and others, and a display device 304 which displaysinput/output information.

To the memory 303 are connected a stage drive mechanism informationstorage device 306 which stores a program required to automatically movethe stage 228, on which the crystallization target substrate 227 as anon-single-crystal semiconductor film is mounted, in accordance with apredetermined procedure, a pulsed laser beam source 221 which outputs apulsed laser beam for crystallization, and a laser apparatus controlinformation storage device 307 which stores a program required tocontrol an attenuator 222.

Additionally, the memory 303 includes a measurement/analysis informationstorage device 308 which stores a program required to measure a lightintensity of each pulsed laser beam emitted from the pulsed laser beamsource 221 and judges whether the pulsed laser beam is applied to thenext irradiation position when the measured value is not smaller than aspecified value and whether a pulsed laser beam irradiation process isagain required when the measured value is not greater than the specifiedvalue, a normal laser beam information storage device 309 which stores apreviously obtained light intensity for crystallization as normal lightintensity information, and an irradiation information storage device 310which stores a measurement result.

An embodiment of the crystallization process will now be described withreference to FIGS. 13A and 15. First, before executing thecrystallization process, the CPU 302 reads a program stored in thememory 303, performs control to move the crystallization targetsubstrate 227 from an optical path of the laser beam 220 or the samplestage 228 which supports this crystallization target substrate 227 to apredetermined retraction position, thereby positioning thecrystallization target substrate 227. Then, the CPU 302 reads acrystallization program from the memory 303, and controls emission ofthe pulsed laser beam set to have a crystallization light intensity fromthe laser beam source 221.

The emitted laser beam is divided into a detection laser beam and acrystallization laser beam by an optical component such as a halfmirror, and the detection laser beam is detected by the photodetector229. The CPU 302 stores light intensity information detected by thisphotodetector 229 in the memory 303. The CPU 302 reads data from themeasurement/analysis information storage device 308 and the normal laserbeam information storage device 309, compares the read data with thedetected light intensity information, outputs judgment informationindicating that the light intensity is within or out of a normal range,and stores it in the memory 303 in association with irradiation positioninformation.

If it is determined that the light intensity is within the normal range,the CPU 302 displays this result in the display device 304, and storesit in the normal laser beam information storage device 309. At the sametime, the CPU 302 reads a program required to move the sample stage 228from the stage drive mechanism information storage device 306, andcontrol information required move the sample stage 228 to the nextirradiation position to the drive mechanism DM.

On the other hand, if it is determined that the light intensity is notgreater than the specified value and it is out of the normal range, theCPU 302 displays this judgment information as an output defective shotin the display device together with the irradiation positioninformation, and stores it in the measurement/analysis informationstorage device 308. At the same time, the CPU 302 likewise stores thisirradiation position as a light intensity insufficient irradiationposition in the stage drive mechanism information storage device 306.When a series of irradiation process of the crystallization targetsubstrate 227 which is a non-single-crystal semiconductor film isfinished, the CPU 302 calls previously stored irradiation positioninformation which is not greater than the specified value (the lightintensity insufficient irradiation position information), reads a laserapparatus control program from the laser apparatus control informationstorage device 307, and drives the stage 228 to move to a lightintensity insufficient irradiation position, thereby again executingapplication control. Then, the excimer laser beam source 221 iscontrolled to again control emission of the laser beam. Such acrystallization process is repeated to execute the predeterminedextensive crystallization process.

FIG. 16 shows a concrete specified value determination flowchart. Aprocedure of determining a specified value will now be described withreference to FIG. 16. The crystallization target substrate 227 isirradiated with the laser beam while sequentially increasing a laserintensity F (a laser fluence F), and a threshold value which is aspecified value with which crystallization can be sufficiently carriedout is determined based on actual measurement. First, an increasequantity (ΔF) of a laser beam intensity is determined (a step 262).Then, an upper limit value (Fup) of the laser beam intensity isdetermined (a step 263). This is determined while considering anoscillation capability of the excimer laser beam source 221, anappropriate range at the time of continuous crystallization processing,a crystallization margin and others. The crystallization targetsubstrate 227 is irradiated with the laser beam having a laser intensityto which the increase quantity ΔF is sequentially added (steps 264 and265), the stage 228 is sequentially moved (a step 266), the laser beamirradiation processing for crystallization is continued, and theprocessing is stopped when the laser intensity reaches the upper limitvalue Fup (a step 267).

The crystallization target substrate 227 is taken out, and crystallinityis evaluated at the next step (a step 268). This is an off-lineevaluation, and this embodiment performs processing based onSecco-etching (this is one of methods which optically evaluates a defectof a silicon crystal, and a method which performs etching processing byusing a mixed chemical of HF and K₂Cr₂O₇) to evaluate crystallinity.

FIG. 17 shows the crystallization target substrate 227 subjected to theirradiation processing. Numeric symbols “1”, “5”, “6”, “8” . . . denotean order of the irradiation processing, and each rectangle indicates aprocessing region based on laser irradiation for one time. It wasconfirmed that crystallization does not sufficiently occur in regionsdenoted by the numeric symbols “1” to “5”, and these regions areindicated by dotted lines. Therefore, in this case, an intensity of thelaser beam applied for the sixth time is a threshold value of thespecified value, and a laser intensity which is not smaller than thisthreshold value is determined as the specified value (a step 269).

Although this experiment obtains an influence of amorphous thin filmforming conditions on the specified value and thereby determines thespecified value of the photodetection value while taking acrystallization evaluating method based on an electron backscatteringprocess or TEM as an example, the present invention is not restricted tothis method. For example, a light reflection factor of an irradiationtarget film after irradiation processing greatly differs depending on anamorphous state and a crystallized state, and the specified value may bedetermined with such a variable light reflection factor being used as anindex. As described above, the specified value is determined based onvarious kinds of experimental measurement (a grain diameter of a crystalgrain (a scanning electron microscope (SEM), a transmission electronmicroscope (TEM)), measurement of crystallinity (an electronbackscattering process (EBSP), an X-ray diffraction method (XRD), areflection high energy electron diffraction method (RHEED)), and acrystallized status (a change in a light reflection factor before andafter processing, a change in electrical characteristics by using afour-terminal measurement method or the like, a change in an absorptionfactor of an infrared region using FTIR). Further, the present inventionis not restricted to these measurement methods, and any crystallinityevaluating experiment which evaluates crystallinity can be used as meansfor determining the specified value.

Furthermore, in the above-described crystallinity evaluating experiment,its evaluation takes time, and hence it is difficult to immediately givefeedback in the current processing process. Moreover, innon-single-crystal semiconductor films, when a once-set specified valueis continuously used in a step of continuously processingnon-single-crystal semiconductor films having the same elementconfiguration (a film thickness, a film quality and film formingconditions of an amorphous thin film, a film thickness and a filmquality of an insulating film, an element design and others), anoperation of manually inputting the same specified value to the computer231 or an operation of performing calculations by using the computer 231can be eliminated, thereby providing an effective method in an allowablerange of environmental variables.

Eighth and Ninth Embodiments

A description will now be given as to other embodiments which use, asdetection light, a part of a crystallization laser beam emitted from alaser beam source 221 as laser beam detecting means for detectingwhether the laser beam is a laser beam having a predetermined specifiedvalue. FIG. 13B shows an eighth embodiment, and FIG. 13C shows a ninthembodiment. Like reference numerals denote parts equal to those in FIG.13A, thereby eliminating their detailed explanation. In the seventhembodiment (FIG. 13A), the photodetector 229 was arranged in atransmission optical path of the half mirror 225 and, for example, alight intensity of a laser beam transmitted through the half mirror 225was detected. However, the photodetector 229 is not restricted to thisposition.

In the eighth embodiment, as shown in FIG. 13B, reflected lightgenerated when controlling a transmitted light intensity to apredetermined value by adjusting a reflected light quantity in anattenuator 222 is determined as a detection laser beam 220 b, this beamis detected by the photodetector 229, and a signal having aphotodetection value of the detected beam is transmitted to a computer231 through a signal line 230. In this case, the half mirror 225 doesnot have to be used, and using a regular total reflection mirror 225 acan suffice. The computer 231 likewise executes a step of comparing adetection value obtained by the photodetector 229 with a specified valueand detecting whether the laser beam is normal or abnormal in accordancewith laser oscillation from a laser beam source 221.

In the ninth embodiment, as shown in FIG. 13C, a half mirror 225 b isset between an attenuator 222 and a homogenizing optical system 223,reflected light from the half mirror 225 b is determined as a detectionlaser beam 220 b so that, e.g., a light intensity of this beam isdetected by a photodetector 229, and a signal having this photodetectionvalue is transmitted to a computer through a signal line 230. The halfmirror 225 b used in the ninth embodiment transmits almost all laserbeams 220 emitted from a laser beam source 221 therethrough as acrystallization laser beam 220 a. The transmitted light is used forcrystallization as the crystallization laser beam 220 a for acrystallization target substrate 227. Remaining reflected weak light isdetected by the photodetector 229 as a detection laser beam 220 b.Therefore, although reference numerals 225 and 225 b in both FIGS. 13Aand 13C denote the half mirrors, their usages of transmission factorsand reflection factors are different from each other in these twoembodiments.

As described above, light traveling from the laser beam source 221 cansuffice for the photodetector 229, and an optical path position of thelaser beam source 221 is not restricted. However, it is desirable thatan optical component is set in an optical path of the attenuator 222 andthe following elements and the photodetector 229 detects light separatedby, e.g., reflecting or transmitting means from the set opticalcomponent. That is because energy density is controlled.

10th and 11th Embodiments

A description will now be given as to embodiments in which laser beamdetecting means detects whether a laser beam is a laser beam having apredetermined specified value from a surface processed by the laser beamwith reference to FIGS. 13D and 13E. In the seventh to ninthembodiments, the photodetector 229 performs detection, and aphotodetection value of the photodetector 229 is measured to detect anabnormal shot. As 10th and 11th embodiments, a part irradiated with acrystallization laser beam 220 a is directly observed to judge whetherthis part is crystallized, a position of this part is determined as alight intensity insufficient irradiation position when crystallizationis insufficient, and laser beam irradiation processing is againperformed.

First, FIG. 13D shows the 10th embodiment. Like reference numeralsdenote parts equal to those in FIGS. 1 and 13A, thereby eliminatingtheir detailed explanation. As shown in FIG. 13D, a measuring instrument229 a which measures a surface state of a crystallization targetsubstrate 227 is used to measure a change in a light receiving region,i.e., a surface state of an amorphous silicon thin film 227 c afterlaser beam irradiation, and measurement, e.g., imaging is performed tograsp “whether a light receiving region is melted”, “how muchcrystallization is performed” and “whether crystallization isperformed”. As the measuring instrument 229 a, it is possible to use acolor-difference meter, a spectral color-difference meter, a glossmeter, a reflectivity meter, a multi-channel spectrometer, a CCD camera,an image intensifier and others for the surface of the crystallizationtarget substrate 27 to measure changes in optical characteristics suchas a change in color, a change in gloss, a change in reflection factorand others of a crystallized thin film. According to this embodiment, itis possible to detect whether an abnormal shot is present by using anindependent optical system without being affected by a laser beam havinga large crystallization energy quantity.

In case of the 10th embodiment, as shown in a process flowchart of FIG.18, a step (346) of measuring an irradiation part substitutes for thestep (245) of measuring a light intensity by the photodetector in theprocess flowchart depicted in FIG. 14. In regard to any other steps,evaluation is carried out along the same steps as those shown in FIG.14.

FIG. 20 shows a relationship between a light intensity and acrystallization ratio of the crystallization laser beam 220 a. FIG. 19shows a result obtained by measuring a reflection factor whenirradiating a film, whose crystallization factor depicted in FIG. 20 ischanged, with an He—Ne laser beam (632.8 nm). As a result,characteristics of FIG. 19 shows that measuring, e.g., a reflectionfactor of light can grasp a crystallization state of this part since thereflection factor of the light increases when a crystallization factorbecomes high.

In the 11th embodiment, observation illumination light is applied aslaser beam detecting means for detecting whether a laser beam is a laserbeam having a predetermined specified value, and reflected light of thislight is received and detected. In FIG. 13E, an amorphous silicon film227 c is irradiated with a laser beam 220 from an excimer laser beamsource 221, and a light receiving region of the amorphous silicon film227 is melted in case of normal light which is not smaller than thespecified value. This melted region or a crystallized region isirradiated with the observation illumination light from an observationillumination light source 234, and reflected light from the meltedregion or the crystallized region irradiated with the observationillumination light is detected by a detector (an optical receiver) 229a. When the laser beam 220, e.g., an excimer laser beam is normal,reflected light from the melted region or the crystallized region isdetected by the detector 229 a. On the other hand, when the excimerlaser beam is an abnormal shot, the amorphous silicon film 227 c isirradiated with, e.g., the observation illumination light alone.Reflected light obtained at this moment is detected by the detector 229a, the detector 229 a outputs a detection signal to a computer 231, andthe computer 231 determines abnormal irradiation. In this manner, achange in a laser beam irradiation position in the non-single-crystalsemiconductor film can be detected by using the reflected light.

Although the observation illumination light may be continuously applied,a change in the non-single-crystal semiconductor film may be detectedbased on the reflected light in association with a laser beamirradiation timing.

As the observation illumination light source 234, for example, a whitelight source (a xenon lamp, a tungsten lamp or the like) or a low-outputlaser (an He—Ne laser or the like) is set, and the reflected light ismeasured, thereby realizing further accurate measurement. Further, thismeasurement does not have to be carried out at a position irradiatedwith the laser beam for crystallization, and any other parts aresequentially irradiated with the laser beam after the foregoingirradiation. It is good enough to measure a surface state at a placeapart from a crystallized position. Furthermore, reflected light andstray light from the crystallization excimer laser beam are reduced thatway, thereby achieving accurate measurement.

12th Embodiment

A description will now be given as to an embodiment which performsdetection from light obtained by transmitting a laser beam through acrystallization target substrate 227 as laser beam detecting means fordetecting whether the laser beam is a laser beam having a predeterminedspecified value. FIG. 13F shows a 12th embodiment. Like referencenumerals denote parts equal to those in FIG. 13A, thereby eliminatingtheir detailed explanation. When a substrate of the crystallizationtarget substrate 227 is a transparent substrate such as glass, measuringtransmitted light can measure a crystallization state of this thin film.A transmitted light detector 229 b shown in FIG. 13F can be used tomeasure light transmitted through the crystallization target substrate227, and a crystallization factor can be measured by utilizing atransmission factor of the measured light.

According to the foregoing embodiment, even if an abnormal shot occursin irradiation of a laser beam for crystallization, lasercrystallization can be excellently effected by detecting this shotwithout lowering a yield ratio.

A crystallization process used in this experiment will now be concretelydescribed with reference to FIGS. 21 and 22. As shown in FIG. 21, alaser crystallization apparatus 201 comprises: an illumination system202; an optical element 224 provided on an optical axis of thisillumination system 202; an image forming optical lens system 226provided on an optical axis of this optical element 224; acrystallization target substrate 227 provided on an optical axis of thisimage forming optical lens system 226; and a stage (a sample stage) 228which supports the substrate.

The illumination system 202 is an optical system shown in FIG. 22, andconstituted of, e.g., a light source 221, an attenuator 222, a beamexpander 225 and a homogenizing optical system 223. The excimer laserbeam source 221 includes an XeCl excimer laser beam source 221 whichsupplies light having a wavelength of, e.g., 308 nm. It is to be notedthat, as the light source 221, an excimer laser such as a KrF excimerlaser which emits pulse light having a wavelength of 248 nm or an ArFlaser which emits pulse light having a wavelength of 193 nm is optimum.Furthermore, the light source 221 may be a YAG laser beam source. As thelight source 221, it is possible to use any other appropriate lightsource which outputs an energy which fuses a non-single-crystalsemiconductor film, e.g., an amorphous silicon film 227 c. Theattenuator 222, the beam expander 225 and the homogenizing opticalsystem 223 are provided on an optical axis of a laser beam emitted fromthe light source 221.

As shown in FIG. 22, the homogenizing optical system 223 has aconfiguration in which, e.g., a first fly-eye lens 223 a, a firstcondenser optical system 223 b, a second fly-eye lens 223 c and a secondcondenser optical system 223 d are provided on an optical axis of theexcimer laser beam emitted from the light source 221. The homogenizingoptical system 223 homogenizes a light intensity of the laser beamemitted from the light source 221 in a cross section of a light beam.

That is, in the illumination system 202, the laser beam emitted from thelight source 221 is shaped through the attenuator 222 and the beamexpander 225, and then enters the first fly-eye lens 223 a. A pluralityof light sources are formed on a rear focal plane of this first fly-eyelens 223 a, light beams from the plurality of light sources illuminatean incidence surface of the second fly-eye lens 223 c through the firstcondenser optical system 223 b in a superimposing manner. As a result,more light sources are formed on a rear focal plane of the secondfly-eye lens 223 c than those on the rear focal plane of the firstfly-eye lens 223 a. Light beams from many light sources formed on therear focal plane of the second fly-eye lens 223 c fall on the opticalelement 224 through the second condenser optical system 223 c, andilluminate this element in a superimposing manner. The first fly-eyelens 223 a and the first condenser optical system 223 b of thehomogenizing optical system 223 constitute a first homogenizer, and thesecond fly-eye lens 223 c and the second condenser optical system 223 dof the same constitute a second homogenizer. These two homogenizers areused to homogenize a light intensity at each in-plane position on theoptical element 224. In this manner, the illumination system 202 forms alaser beam having a substantially homogeneous light intensitydistribution, and the optical element 224 is irradiated with this laserbeam.

The optical element 224 is an optical component having a function ofshaping a light intensity distribution, and it may be, e.g., a metalmask having a rectangular opening portion, or an optical mask having, asa base material, quartz or the like obtained by depositing anon-translucent material on a translucent optical component such asquartz and removing the non-translucent material in a rectangular shapeby etching. Moreover, the optical element 224 may be, e.g., a phaseshifter, and the phase shifter is an optical element which emits a laserbeam having an arbitrary light intensity distribution by locallymodulating a phase of light exiting from the homogenizing optical system223.

The phase shifter is obtained by forming a step (irregularities) on atransparent body, e.g., a quartz substrate. In general, assuming that awavelength of a laser beam is λ, when a transparent medium having arefraction factor n is formed on the transparent substrate to provide aphase difference of θ, a film thickness t of the transparent medium isgiven by an expression t=λ·θ/(2π(n−1)). Assuming that a refractionfactor of the quartz substrate is 1.46, since a wavelength of an XeClexcimer laser beam is 308 nm, a step of 334.8 nm is formed by a methodof photo-etching or the like in order to provide a phase difference of180°. An intensity of a laser beam transmitted through the phase shifterhaving a line-and-space pattern, e.g., a phase difference of 180°demonstrates a periodic strong-and-weak pattern.

Additionally, in case of forming a film with an SiNx film being used asa transparent medium by PECVD, LPCVD or the like, assuming that arefraction factor of the SiNx film is 1, it is good enough to form theSiNx film with a film thickness of 154 nm on the quartz substrate andperform photo-etching to provide a step.

The laser beam subjected to phase modulation in the optical element 224falls on the crystallization target substrate 227 through the imageforming optical lens system 226. Here, the image forming optical lenssystem 226 is arranged in such a manner that a pattern surface of theoptical element 224 and the crystallization target substrate areoptically conjugate. In other words, a height position of the stage 228is corrected so that the crystallization target substrate 227 is set ona surface (an image surface of the image forming optical lens system226) which is optically conjugate with the pattern surface of theoptical element 224. The image forming optical lens system 226 includesan aperture diaphragm 226 c between a positive lens group 226 a and apositive lens group 226 b. The image forming optical lens system 226 isan optical lens which maintains a size of an image of the opticalelement 224 or reduces the same to, e.g., ⅕ and forms the obtained imageon the crystallization target substrate 227.

Additionally, as shown in FIG. 21, a silicon oxide layer as anunderlying insulating layer 227 b is formed on a glass substrate 227 awhich is, e.g., liquid crystal display glass by a chemical vapordeposition method (CVD) or a sputtering method. A non-single-crystalsemiconductor film 227 c, e.g., an amorphous silicon film is formed as acrystallization target layer on this silicon oxide layer. Further, asilicon oxide layer 227 d as a cap film is sequentially formed on thisamorphous silicon film, thereby obtaining the crystallization substrate227.

The underlying insulating layer 227 b is formed of, e.g., SiO₂ with afilm thickness of 200 to 1000 nm. The underlying insulating layer 227 bprevents a foreign particle from entering the amorphous silicon film 227c, the foreign particle being Na or the like separated out from theglass substrate 227 a when the non-single-crystal semiconductor film 227c, e.g., an amorphous silicon film directly comes into contact with theglass substrate 227 a. Furthermore, the underlying insulating layer 227b also prevents a melting temperature during the crystallization processof the amorphous silicon film 227 c from being directly transmitted tothe glass substrate 227 b, and hence it contributes to crystallizationwith a large grain diameter by a thermal storage effect of the meltingtemperature.

The amorphous silicon film 227 c is a film subjected to crystallizationprocessing, and its film thickness is selected to be 30 to 260 nm, e.g.,100 nm. The cap film 227 d stores heat generated when the amorphoussilicon film 227 c is melted at the crystallization step, and thisthermal storage function distributes to formation of a crystallized areawith a large grain diameter. This cap film is an insulating film, e.g.,a silicon oxide film (SiO₂), and its film thickness is 100 to 400 nm,e.g., 170 nm.

The crystallization target substrate 227 is automatically carried ontothe stage 228 of the laser crystallization apparatus 1, located andmounted at a predetermined position, and held by a vacuum chuck.

The crystallization process will now be described with reference toFIGS. 21 and 22. A pulsed laser beam emitted from the excimer laser beamsource 221 is adjusted to have a predetermined energy, e.g., 700 mJ/cm²by the attenuator 222, and then enters the homogenizing optical system223. The homogenizing optical system 223 homogenizes a light intensitywithin a beam diameter of the incident laser beam.

The laser beam is an XeCl excimer laser beam having a wavelength of 308nm, and pulse duration of one shot is 30 nsec. When the optical element224 is irradiated with the pulsed laser beam under the above-describedconditions, the pulsed laser beam which has entered the optical element224 provokes diffraction and interference at a step portion. As aresult, the optical element 224 generates a strong-and-weak lightintensity distribution with an inverse peak pattern shape indicativewhich periodically varies.

It is desirable to output a laser beam intensity with which theamorphous silicon layer 227 c is melted in a range from the minimumlight intensity to the maximum light intensity in this strong-and-weaklight intensity distribution with the inverse peak pattern shape. Thepulsed laser beam transmitted through the optical element 224 iscondensed on the crystallization target substrate 227 by the imageforming optical lens system 226 and enters the amorphous silicon film227 c.

That is, the incident pulsed laser beam is transmitted through almostall of the silicon oxide layer 227 d as the cap film, and absorbed intothe amorphous silicon film 227 c. As a result, an irradiation targetregion of the amorphous silicon film 227 c is heated and melted. Heatgenerated from melting is stored in the silicon oxide layers 227 b and227 d.

Upon completion of irradiation of the pulsed laser beam, a temperaturein the irradiation target region of the amorphous silicon film 227 c isgoing to be lowered at a high speed, but heat stored in the cap film 227d and the underlying insulating layer 227 b provided on both front andrear sides greatly slows down a temperature reduction speed. At thistime, a temperature in the irradiation target region is reduced inaccordance with the light intensity distribution generated by theoptical element 224, and a crystal sequentially grows in a lateraldirection.

In this manner, the crystallization step using one pulsed laser beam isterminated. As described above, a crystal grain having a size which issufficient to form one or more TFTs is formed.

The crystallization apparatus 201 automatically irradiates the nextcrystallization target region of the amorphous silicon film 227 c withthe pulsed laser beam based on a previously stored program, therebyforming a crystallized region. Movement to the next crystallizationtarget position can be effected by moving the stage 228 so that thecrystallization target position can be selected.

When the crystallization target region is selected and positioning isfinished, the next pulsed laser beam is emitted. Repeating such a laserbeam shot, a large area in the crystallization target substrate 27 canbe crystallized. In this manner, the crystallization step can beterminated.

An embodiment of a TFT and a display device using this TFT will now bedescribed with reference to FIGS. 23 and 24. First, a configuration anda manufacturing method of an embodiment of a thin film transistor (TFT)will be described. Like reference numerals denote parts equal to thosein FIGS. 1 and 13A to 22, thereby eliminating their tautologicaldetailed explanation.

A thin film transistor 280 was formed on a crystallization targetsubstrate 227 having a crystalline silicon film 281 (an amorphoussilicon film 227 c) whose crystal grain was increased in size by thecrystallization apparatus 201 shown in FIG. 21. That is, a cap film 227d was removed by etching, then etching was performed in such a mannerthat a channel region of each TFT can remain in an island shape in eachcrystallization target region (a crystalline silicon film) of thecrystalline silicon film whose crystal grain was increased in size. Inthis manner, an Si island having a predetermined pattern was formed on asubstrate 227 a.

Then, a gate insulating film 282 is formed on the crystalline siliconfilm 281. The gate insulating film 282 is formed of a material mainlycontaining silicon oxide (SiO₂) or silicon oxynitride (SiON). This gateinsulating film 282 is obtained by forming a silicon oxide film having athickness of, e.g., 30 to 120 nm. This silicon oxide film is the gateinsulating film 282 formed of SiH₄ and N₂O as raw materials with athickness of 50 nm by, e.g., a plasma CVD method.

Then, an electroconductive layer is formed in order to constitute a gateelectrode 283 on the gate insulating film 282. This electroconductivelayer is formed of a material mainly containing an element such as Ta,Ti, W, Mo or Al by using a known film forming method such as asputtering method or a vacuum evaporation method. As the gate electrode283, an Al—Ti ally film was formed. As to this Al—Ti alloy film, a gateelectrode metal layer was patterned by using photolithography to formthe gate electrode 283 having a predetermined pattern.

Then, a source region 284 and a drain region 285 were formed byion-implanting an impurity required to form the source region 284 andthe drain region 285 into the crystalline silicon film 281 with the gateelectrode 283 being used as a mask. As to a source region 252 b and adrain region 252 c, in case of forming, e.g., a p channel type TFT, a ptype impurity such as a boron ion is implanted by using an ionimplantation method. A boron concentration in this region was set to,e.g., 1.5×10²⁰ to 3×10²¹. In this manner, a high-concentration p typeimpurity region constituting each of the source region 84 and the drainregion 85 of the p channel type TFT was formed. In regard toimplantation of an impurity, it is needless to say that implanting an ntype impurity can form an n channel type TFT. As a result, a crystallinesilicon film 81 below the gate electrode 83 becomes a channel region 86by forming the source region 84 and the drain region 85.

Then, a heat treatment process was carried out in order to activate theimpurity element implanted by the ion implantation method. This processcan be performed by a furnace crystallization method, a lasercrystallization method, a rapid thermal crystallization method or thelike. In this embodiment, the activation process was conducted by thefurnace crystallization method. In regard to a heat treatment of thisactivation process, the heat treatment was performed at 300 to 650° C.,e.g., 500° C. in a nitrogen atmosphere for four hours.

Then, an interlayer insulating film 287 is formed on the gate insulatingfilm 282 including the upper side of the gate electrode 83. As theinterlayer insulating film 287, it is desirable to use a laminated filmformed of, e.g., a silicon nitride film, a silicon oxide film, a siliconoxynitride film or a combination of these films. Further, it is goodenough to set a film thickness of the interlayer insulating film 287 to200 to 600 nm, and 400 nm was selected in this embodiment.

Then, each contact hole 88 which is in contact with an electrode of thesource region 284 or the drain region 285 was formed at a predeterminedposition of the interlayer insulating film 287. Then, anelectroconductive layer was formed in the contact hole 288 and on thesurface of the interlayer insulating layer 287, and a source electrode290 and a drain electrode 291 were formed. In this embodiment, theelectroconductive layer for the source and drain electrodes 290 and 291is a laminated film having a three-layer configuration obtained bycontinuously forming, e.g., a Ti film with a thickness of 100 nm, analuminum film containing Ti with a thickness of 300 nm and a Ti filmwith a thickness of 150 mm by a sputtering method. The thin filmtransistor 280 shown in FIG. 23 was manufactured in this manner.

Then, a description will now be given as to an example in which the thinfilm transistor 280 obtained in the above embodiment is actually appliedto a display device, e.g., an active matrix type liquid crystal displaydevice with reference to FIG. 24.

FIG. 24 is a view illustrating an example of an active matrix typedisplay device using the thin film transistor 280. A display device 400has a panel configuration including an electro-optic material 403 heldbetween a pair of opposing insulating substrates 401 and 402. As theelectro-optic material 403, a liquid crystal material is extensivelyused. A pixel array portion 404 and a drive circuit portion areintegrated and formed on the lower insulating substrate 401, e.g., aglass substrate. The drive circuit portion is divided into a verticaldrive circuit 405 and a horizontal drive circuit 406, and they areintegrated around the pixel array portion 404. That is, the pixel arrayportion 404 and the drive circuit portion can be formed on one glasssubstrate.

Furthermore, terminal portions 407 for external connection are formed ata peripheral upper end of the insulating substrate 401. The terminalportions 407 are connected with the vertical drive circuit 405 and thehorizontal drive circuit 406 through wirings 408. Gate wirings 409 inrows and signal wirings 410 in columns are formed on the pixel arrayportion 404. A pixel electrode 411 and a thin film transistor 480driving this electrode are formed at each intersection of these wirings.A gate electrode 283 of the thin film transistor 280 is connected with acorresponding gate wiring 409, a source electrode 290 of the same isconnected with a corresponding signal wiring 410, and a drain electrode291 of the same is connected with a corresponding pixel electrode 411.The gate wiring 409 is connected with the vertical drive circuit 405and, on the other hand, the signal wiring 410 is connected with thehorizontal drive circuit 406.

The thin film transistor 280 which drives the pixel electrode 411 to beswitched and the thin film transistor included in each of the verticaldrive circuit 405 and the horizontal drive circuit 406 are manufacturedin accordance with the present invention, and their mobility is higherthan that in the prior art. Therefore, it is possible to integrate andform not only the drive circuit but also a processing circuit havinghigher performance.

An embodiment shown in FIGS. 25 and 26 is an embodiment in which aregion in which a switching circuit provided in each pixel portion 326is formed is selectively crystallized in a non-single-crystalsemiconductor film formed in a display panel 325 of an active matrixtype display device. FIG. 25 is a partially cutaway plan view of thedisplay panel 325, showing a state in which a stage 228 having acrystallization target substrate 227 mounted thereon is step-fed at afixed pitch in the form a rectangular pattern.

This embodiment is an embodiment in which a laser beam 220 is emittedfrom a laser beam source 221 to thereby effect crystallization only whenthe stage 228 is step-fed to each pixel portion 326 alone which is eachintersection of data lines X and scanning lines Y in FIG. 25. That is,this is an example in which the laser beam source 221 emits the laserbeam 220 only when the stage 228 is step-fed to each pixel portion only,and a standby mode begins without emitting the laser beam 220 when thestage 228 is step-fed to a part between the respective pixel portions326. In this control, the stage 228 having the display panel 325 mountedthereon is controlled by a program previously stored in a computer 231with which a crystallization apparatus automatically executes acrystallization process, and a laser oscillation control signal isoutput to the laser beam source 221 when a signal of a positioncorresponding to the pixel portion 326 is received from the pixel panel325 mounted on this stage 228. The computer 231 does not output thelaser oscillation control signal to the laser beam source 221 when asignal of a position corresponding to a space between the respectivepixel portions from the display panel 325 mounted on the stage 228 isreceived.

In this manner, when the stage 228 is step-fed to a part between therespective pixel portions 326, the laser beam source 221 enters thestandby mode without emitting the laser beam 220 and, in thisembodiment, this is a case where this state is not stored as abnormalshot position information. That is, this embodiment is a case where atiming at which no laser beam is emitted from the laser beam source 221is preset as a normal operation and this operation is not determined asabnormal shot position information. This operation can be constituted bypreviously programming unnecessariness for application of the laser beamin the computer 231.

Moreover, FIG. 26 shows an embodiment in which programming is performedin advance in such a manner that a stage 228 having a display panel 325mounted thereon is supplied at a pitch of respective pixel portions 326which are regularly provided. This embodiment is an example in whichwhether a predetermined quantity of a laser beam 220 is emitted from alaser beam source 221 is monitored at a position to which the stage 228is step-fed and the laser beam is reapplied at a later step.

Additional advantages and modifications will readily occur to thoseskilled in the art. Therefore, the invention in its broader aspects isnot limited to the specific details and representative embodiments shownand described herein. Accordingly, various modifications may be madewithout departing from the spirit or scope of the general inventionconcept as defined by the appended claims and their equivalents.

1. A processing apparatus using a pulsed laser beam, comprising: a laserbeam source which emits a pulsed laser beam; a homogenizer opticalsystem which homogenizes an intensity of the laser beam emitted from thelaser beam source in a two-dimensional plane; a irradiating section forirradiating a position of a processing target with the homogenizedpulsed laser; a monitoring section for monitoring an intensity of lightreflected by the processing target; a mechanism for irradiating the nextirradiation position of the processing target with a homogenized pulsedlaser beam when it is determined that the light intensity is normal as aresult of monitoring by the monitoring section; and a mechanism foragain irradiating an insufficient position of the processing target witha homogenized pulsed laser when it is determined that the lightintensity is insufficient as a result of the monitoring by themonitoring section.
 2. A processing apparatus using a pulsed laser beam,comprising: a laser beam source which emits a pulsed laser beam; ahomogenizer optical system which homogenizes an intensity of the laserbeam emitted from the laser beam source in a two-dimensional plane;processing section for irradiating a processing target with thehomogenized laser beam to subject the processing target to laserprocessing; an optical monitoring portion which optically monitors aprocessing state of an irradiation position in accordance with thepulsed laser beam emitted from the laser beam source; first mechanismfor irradiating a next irradiation position of the processing targetwith the pulsed laser beam when it is determined that a processing stateis normal as a result of the monitoring; and second mechanism forirradiating for again irradiating a non-normal processing position ofthe processing target when it is determined that a processing state isnon-normal as a result of the monitoring.
 3. A laser crystallizationapparatus which irradiates a non-single-crystal semiconductor film witha laser beam emitted from a laser which performs pulsed oscillation tothereby carry out crystallization, having: laser beam detecting sectionfor detecting whether the laser beam is a laser beam having apredetermined specified value; and a computer which compares a detectionvalue detected by the laser beam detecting section with thepredetermined specified value, stores irradiation position informationof the non-single-crystal semiconductor film as abnormal shot positioninformation when the detection value does not fall within a range of thespecified value, reads the abnormal shot position information whenanother light receiving region is irradiated with the laser beam andlaser beam irradiation of the non-single-crystal semiconductor film isterminated, and again issues a laser beam irradiation command toirradiate the abnormal shot position.
 4. A laser crystallizationapparatus which irradiates a non-single-crystal semiconductor film witha laser beam emitted from a laser which performs pulsed oscillation tothereby carry out crystallization, having: a laser beam source whichperforms pulsed oscillation with respect to the laser beam; ahomogenizer optical system which is provided in a laser optical pathfrom the laser beam source, and homogenizes an intensity of the laserbeam in a two-dimensional space; an optical element which is provided ina laser optical path from the homogenizer optical system, and forms alight intensity gradient in the homogenized laser beam; a sample stagewhich is provided in a laser optical path from the optical element, onwhich a non-single-crystal semiconductor film, whose light receivingregion is at least partially melted when the laser beam is received, ismounted thereon, and which is configured to move to a predeterminedother light receiving region; laser beam detecting section for detectingwhether the laser beam is a laser beam having a predetermined specifiedvalue; and a computer which compares a detection value detected by thelaser beam detecting section with the predetermined specified value,stores irradiation position information of the non-single-crystalsemiconductor film as abnormal shot position information when thedetection value does not fall within a range of the specified value,reads the abnormal shot position information when another lightreceiving region is irradiated with the laser beam and laser beamirradiation of the non-single-crystal semiconductor film is terminated,and again issues a laser beam irradiation command to irradiate theabnormal shot position.
 5. A display device using a crystallizationmethod which irradiates a non-single-crystal semiconductor film with alaser beam emitted from a laser beam source which performs pulsedoscillation to thereby carry out crystallization, the crystallizationmethod having: a homogenization processing step of homogenizing anintensity of a laser beam in a two-dimensional space; a step of forminga light intensity gradient in an intensity distribution of the laserbeam subjected to the homogenization processing; a laser beamirradiation step of irradiating the non-single-crystal semiconductorfilm with the laser beam having the light intensity gradient formedtherein; a laser beam detection step of detecting whether the laser beamis a laser beam having a predetermined specified value; an abnormal shotposition information storage step of storing an irradiation position ofthe non-single-crystal semiconductor film as abnormal shot positioninformation when the detection value does not fall within a range of thespecified value; and a laser beam re-irradiation step of reading thestored abnormal shot position information and irradiating a positionindicated by the read abnormal shot position information with the laserbeam, wherein a crystallization target region is formed in a regioncorresponding to each predetermined pixel of the non-single-crystalsemiconductor film provided on a substrate, and a transistor is formedin this crystallization target region.